PHP - Session Not Working

		<script>  
			var xhr;
			 if (window.XMLHttpRequest) { // Mozilla, Safari, ...
				xhr = new XMLHttpRequest();
			} else if (window.ActiveXObject) { // IE 8 and older
				xhr = new ActiveXObject("Microsoft.XMLHTTP");
			} 
				xhr.open("POST", "PHPLibrary/selectMemberResults.php", true); 
				xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");                  
				xhr.send();
				xhr.onreadystatechange = display_data;
				var $phparray
				function display_data() {
				 if (xhr.readyState == 4) {
				  if (xhr.status == 200) {
				    //alert(xhr.responseText);	   
					$phparray = xhr.responseText;
					document.getElementById("suggestion").innerHTML = $phparray;
					//
					//
					//......................................................?
					// The above line of code is the last thing to print or 
					// to do anything that returns to the browser....
					//.......................................................?
					// All lines below do nothing............................?

					//
				  } else {
					//alert('There was a problem with the request.');
				  }
				 }
				}   
				document.write("Length of phparray Array :" + $phparray.length + "<");  
				var output = JSON.parse($phparray, function (key,val) {
					if ( typeof val === 'string' ) {
						// regular expression to remove extra white space
						if ( val.indexOf('\n') !== -1 ) {
							var re = /\s\s+/g;
							return val.replace(re, ' ');
						} else {
							return val;
						}
					}
					return val;
				} ); 
				document.write("Length of Array :" + $output.length + "<");
				for (var i=0; i < $output.length; i++)
					{
						document.getElementById("suggestion").innerHTML = $output[i].MEMBER_NAME;
					}  
		</script> 

$name = "img/".rand(1,9999999).".png";
$myFile = $name;
$fh = fopen($myFile, 'w') or die("can't open file");
$stringData = $html;
fwrite($fh, $stringData);
fclose($fh);
$file=$name;
$fst=file_get_contents($file);
$im=imagecreatefromstring($fst);
imagefilter($im, IMG_FILTER_GRAYSCALE);
imagefilter($im, IMG_FILTER_NEGATE);
//Convert to Grey Scale
for($i=0;$i<123;$i++){
for($j=0;$j<50;$j++){
$px=imagecolorat($im,$i,$j);
if($px<0x303030){
imagesetpixel($im,$i,$j,0);
}else{
imagesetpixel($im,$i,$j,0xffffff);
}
}
}
$database = unserialize(@file_get_contents("db.txt"));
if($database === false) $database = array();
// modify the database if needed
if($_SERVER['REQUEST_METHOD'] == 'POST'){
	if($_POST['submit'] == 'Add')
		$database[$_POST['ident']] = substr($_POST['letter'], 0, 1);
	if($_POST['submit'] == 'Del')
		unset($database[$_POST['ident']]);
	if($fh = @fopen('db111.txt', 'w+')){
		fwrite($fh, serialize($database));
		fclose($fh);
}
}else{
$newimage = true;
}
$width   = 130;
$height  = 40;
$captcha_gridstart   =1;
$captcha_gridspace   =2;
$letters = findletters($im, $width, $height, $captcha_gridstart, $captcha_gridspace);
$count   = count($letters);
$cellw   = ($count > 0) ? intval(100 / $count) : 0;
//dispeckle the image and GET co-ordinates of the characters of captcha image and return them. 
function findletters($image, $width, $height, $gridstart, $gridspace){
	$offsets  = array(); $o = 0;
	$atstartx = true;
	for($x = 0; $x < $width; $x++){
		$blankx = true;
		for($y = 0; $y < $height; $y++){
			if(imagecolorat($image, $x, $y) == 0){
				$blankx = false;
				break;
			}
		}
		if(!$blankx && $atstartx){
			$offsets[$o]['startx'] = $x;
			$atstartx = !$atstartx;
		}else if($blankx && !$atstartx){
			$offsets[$o]['endx']   = $x;
			$atstartx = !$atstartx;
			$o++;
		}
	}
	$count = $o;
	for($o = 0; $o < $count; $o++){
		for($y = 0; $y < $height; $y++){
			$blanky = true;
			for($x = $offsets[$o]['startx']; $x < $offsets[$o]['endx']; $x++){
				if(imagecolorat($image, $x, $y) == 0){
					$blanky = false;
					break;
				}
			}
			if(!$blanky){
				$offsets[$o]['starty'] = $y;
				break;
			}
		}
		for($y = $height-1; $y > $offsets[$o]['starty']; $y--){
			$blanky = true;
			for($x = $offsets[$o]['startx']; $x < $offsets[$o]['endx']; $x++){
				if(imagecolorat($image, $x, $y) == 0){
					$blanky = false;
					break;
				}
			}
			if(!$blanky){
				$offsets[$o]['endy'] = $y;
				break;
			}
		}
	}
	for($o = 0; $o < $count; $o++){
		$offsets[$o]['ident'] = "";
		for($x = $offsets[$o]['startx'] + $gridstart; $x < $offsets[$o]['endx']; $x += $gridspace){
			for($y = $offsets[$o]['starty'] + $gridstart; $y < $offsets[$o]['endy']; $y += $gridspace){
				$offsets[$o]['ident'] .= ((imagecolorat($image, $x, $y) == 0) ? "0" : "1");
				#echo $offsets[$o]['ident'].'<br>';
			}
		}
	}
	return $offsets;
}
$a="";
foreach($letters as $letter){
$asciiletter = $database[$letter['ident']];
if(!empty($asciiletter)) {
$a.=$asciiletter;
}
}

I need bit of help, so I am looking into a plugin created for newsletter where default is it shows ad but it has option to remove ads by checking the check box. Default is to send ads in newsletter but if you don't want to send ads through newsletter then check the box. The problem is, it seems like checkbox selected is not being picked up. Some help would be appreciated.

The custom field in wp:

'label' => 'Hide newsletter ads',
           'name' => 'hide_ads', 
          'type'  => 'checkbox',
                'instructions'      => 'Checking the checkbox will remove ads',
                'required'          => 0,
                'conditional_logic' => 0,
                'wrapper'           => array(
                    'width' => '',
                    'class' => '',
                    'id'    => '',
                ),
                'choices' => array(
                    'Hide newsletter ads' => 'Hide newsletter ads',
                ),
                'allow_custom' => 0,
                'default_value' => array(
                ),
                'layout' => 'block',
                'toggle' => 0,
                'return_format' => 'value',
                'save_custom' => 0,
               ),

This is the php code for it:

  <!doctype html>
    <html lang="en-GB">
 <head>
<meta name="viewport" content="width=device-width" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="x-apple-disable-message-reformatting">
<title><?php the_title(); ?></title>
<style>
    <?php require ABSPATH . 'path/newsletter.css'; ?>
</style>
<!--[if mso]>
<style type="text/css">
.outlook-fallback-font {
    font-family: 'Lucida Bright', 'Cambria', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
}
</style>
 <![endif]-->
 </head>

 <?php
$hide_newsletter_ads = get_field('hide_ads');
echo $hide_newsletter_ads;
?>

 <body itemscope itemtype="http://schema.org/EmailMessage">

 <div class="wrap">

    <?php
    if (!$hide_newsletter_ads) {
        include ABSPATH . 'path/ad-banner.php';
        }
    ?>
    <div class="header">
        <a href="<?php bloginfo( 'url' ); ?>">
            <img src="<?php echo get_home_url().'logo.png' ?>" alt="News" 
       />
        </a>
    </div>

    <?php
    if ( have_posts() ) :
        while ( have_posts() ) :
            the_post();
            ?>

            <?php if ( get_field( 'newsletter_summary' ) ) { ?>
                <div class="newsletter-summary"><?php the_field( 'newsletter_summary' ); ?></div>
            <?php } ?>

            <?php if ( have_rows( 'newsletter_content' ) ) : ?>

                <?php
                // Loop through the ACF blocks
                $count = 0;
                while ( have_rows( 'newsletter_content' ) ) :
                    the_row();

                    if ( get_row_layout() === 'story' ) :
                        ?>

                        <?php if ( 0 === $count ) { ?>
                            <span class="date outlook-fallback-font"><?php the_time( 'd M Y' ); ?></span>
                        <?php } ?>

                        <?php if ( get_sub_field( 'story_heading' ) ) : ?>
                            <h1><?php the_sub_field( 'story_heading' ); ?></h1>
                        <?php endif; ?>

                        <div class="content">
                            <?php the_sub_field( 'story_content' ); ?>
                        </div>

                        <?php
                    endif;

                    if ( 'post_list' === get_row_layout() ) :
                        ?>

                        <?php
                        $posts = get_sub_field( 'post_list' );
                        if ( $posts ) :
                            ?>

                        </div>
                        <div class="story-list">
                            <h2><span class="wrap"><?php the_sub_field( 'post_list_heading' ); ?></span></h2>
                            <div class="wrap-table">
                                <table width="100%" cellpadding="0" cellspacing="0" border="0">

                                    <?php
                                    // Output story cards
                                    foreach ( $posts as $i => $post ) {
                                        if ( 0 === $i % 2 ) {
                                            echo '<tr>';
                                        }

                                        $class = ( 0 === $i % 2 ) ? 'odd' : 'even';

                                        $image_src    = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), array( 640, 345 ) );
                                        $image_srcset = wp_get_attachment_image_srcset( get_post_thumbnail_id( $post->ID ) );
                                        echo sprintf(
                                            '<td class="story-cell %4$s" valign="top">
                                            <a href="%1$s" class="story-card outlook-fallback-font">
                                            <img src="%3$s" alt="" height="120" style="height: 150px; object-fit: cover;" />
                                            <span>%2$s</span>
                                            </a>
                                            </td>',
                                            esc_url( get_permalink( $post->ID ) . '?utm_source=newsletter&utm_medium=email&utm_campaign=newsletter' ), // permalink
                                            esc_html( get_the_title( $post->ID ) ), // title
                                            // esc_attr( $image_src[0] ), // image  - src
                                            esc_attr( $image_src[0] ), // image  - src
                                            esc_attr( $class ) // class
                                        );

                                        if ( 0 !== $i % 2 || count( $posts ) === ( $i + 1 ) ) {
                                            echo '</tr>';
                                        }
                                    }
                                    ?>

                                </table>
                            </div>
                        </div>
                        <div class="wrap">
                            <?php
                        endif;
                    endif;

                    if (!$hide_newsletter_ads) {

                     (0 === $count) {
                        include ABSPATH . 'path/mpu-1.php';
                    }

                    if (1 === $count) {
                        include ABSPATH . 'path/mpu-2.php';
                    }
                }

                    $count++;

                endwhile;

            endif;
            ?>

            <div class="footer">
                <table width="100%" cellpadding="0" cellspacing="0" border="0">
                    <tr>
                        <td align="left">
                            &copy;  <?php echo esc_html( date( 'Y' ) ); ?>
                        </td>
                        <td class="footer-link">
                            <a href="<?php echo get_permalink( get_page_by_path( 'privacy-policy' ) ); ?>">Privacy Policy</a> &middot;
                            <a href="%unsubscribe_url%">Unsubscribe</a>
                        </td>
                    </tr>
                </table>
            </div>

        </div>

        <?php
    endwhile;
endif;
?>