This is a simple plugin that can be used to set all child license keys expiration dates to their parent's. This is not for use in production, and is for example purposes only

edd-fix-child-licenses.php

<?php
/*
Plugin Name: Easy Digital Downloads - Fix child licenses
Description: Make the child licenses of all licensed bundles match the parent license expiration
Plugin URI: https://easydigitaldownlaods.com
Author: Phil Johnston
Author URI: https://easydigitaldownloads.com
Version: 1.0
License: GPL2
*/

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

function set_all_child_key_expirations_to_match_bundle_parent() {

	global $wpdb;

	if ( ! isset( $_GET['set_all_child_key_expirations_to_match_bundle_parent'] ) ) {
		return false;
	}

	?>
	<h1>Setting all child license keys to match their parent license key expiration.</h1>
	<h2>Do not close this window until the process has completed</h2>
	<p>
		<div id="current_status">Starting...</div>
	</p>
	<?php

	$table_name = $wpdb->prefix . 'edd_licenses';

	// Query all licenses that have a parent set to get a total count
	$query = $wpdb->prepare( "SELECT DISTINCT( l1.id ) FROM {$table_name} l1 WHERE 1=1 AND l1.parent !=0 AND l1.status != 'private' ORDER BY l1.id ASC LIMIT %d,%d;",
		0,
		0
	);

	$total = count( $query );

	// Output the javascript that will fetch to the server to process each chunk of purchases ?>
	<script type="text/javascript">

	function set_all_child_key_expirations_to_match_bundle_parent( step ) {

		var postData = JSON.stringify({
			step: step,
			total: <?php echo $total; ?>
		});

		fetch( '<?php echo get_bloginfo( 'url' ); ?>/?set_all_child_key_expirations_to_match_bundle_parent_endpoint', {
			method: "POST",
			mode: "same-origin",
			credentials: "same-origin",
			headers: {
				"Content-Type": "application/json"
			},
			body: postData
		} ).then(
			function( response ) {
				if ( response.status !== 200 ) {

					console.log('Looks like there was a problem. Status Code: ' + response.status);

					return;
				}

				// Examine the text in the response
				response.json().then(
					function( data ) {
						if ( data.success ) {

							// If the steps are complete
							if ( data.complete ) {

								document.getElementById("current_status").innerHTML="100% Complete";

							}

							// If the steps are not complete, run the next step. It gets incremented on the server.
							if ( ! data.complete ) {

								document.getElementById("current_status").innerHTML="Step " + data.step + " of " + data.total;

								set_all_child_key_expirations_to_match_bundle_parent( data.step );
							}

						} else {

							document.getElementById("current_status").innerHTML=data.details;

							console.log('Looks like there was a problem. Response from server was: ' + data.details );

						}
					}
				);
			}
		).catch(
			function( err ) {
				console.log('Fetch Error :-S', err);
			}
		);
	}

	set_all_child_key_expirations_to_match_bundle_parent( 0 );

	</script>
	<?php
	die();
}
add_action( 'init', 'set_all_child_key_expirations_to_match_bundle_parent' );

function set_all_child_key_expirations_to_match_bundle_parent_endpoint() {

	global $wpdb;

	if ( ! isset( $_GET['set_all_child_key_expirations_to_match_bundle_parent_endpoint'] ) ) {
		return false;
	}

	$contentType = isset($_SERVER["CONTENT_TYPE"]) ? trim($_SERVER["CONTENT_TYPE"]) : '';
	if ( $contentType !== "application/json" ) {
		echo json_encode( array(
			'success' => false,
			'details' => 'Request was incorrect.'
		) );
		die();
	}
	//Receive the RAW post data.
	$content = trim(file_get_contents("php://input"));
	$decoded = json_decode($content, true);

	//If json_decode failed, the JSON is invalid.
	if( ! is_array( $decoded ) ) {
		echo json_encode( array(
			'success' => false,
			'details' => 'Request was incorrect.'
		) );
		die();
	}
	if ( ! isset( $decoded['step'] ) ){
		echo json_encode( array(
			'success' => false,
			'details' => 'No Step Found'
		) );
		die();
	}

	// Increment the step
	$step = absint( $decoded['step'] ) + 1;
	$number_of_posts_per_step = 10;
	$offset = $step * $number_of_posts_per_step - $number_of_posts_per_step;
	$total = absint( absint( $decoded['total'] ) / $number_of_posts_per_step );
	$table_name = $wpdb->prefix . 'edd_licenses';

	// Query 10 licenses that have a parent set
	$query = $wpdb->prepare( "SELECT DISTINCT( l1.id ) FROM {$table_name} l1 WHERE 1=1 AND l1.parent !=0 AND l1.status != 'private' ORDER BY l1.id ASC LIMIT %d,%d;",
		$offset,
		$number_of_posts_per_step
	);

	$child_license_ids = $wpdb->get_col( $query, 0 );

	if ( empty( $child_license_ids ) ) {
		echo json_encode( array(
			'success' => true,
			'complete' => true,
		) );

		die();
	}

	// loop through each child license
	foreach( $child_license_ids as $child_license_id ) {

		$child_license = edd_software_licensing()->get_license( $child_license_id );

		// Get the parent license of this child license
		$parent_license = edd_software_licensing()->get_license( $child_license->parent );

		$child_license->expiration = $parent_license->expiration;
	}

	echo json_encode( array(
		'success' => true,
		'complete' => false,
		'step' => $step,
		'total' => $total
	) );

	die();

}
add_action( 'init', 'set_all_child_key_expirations_to_match_bundle_parent_endpoint' );