Tell PMPro to wait 15 seconds instead of 5 on AJAX calls

pmpro_ajax_timeout.php

<?php
/**
 * Change the PMPro AJAX timeout limit.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_ajax_timeout($timeout) {
	// Wait 15 seconds.
	return 15000;
}
add_filter('pmpro_ajax_timeout', 'my_pmpro_ajax_timeout');