Change the default text for the one-membership-product-per-cart warning in PMPro WooCommerce.

my_gettext_pmprowc_changes.php

<?php
/**
 * Change the default text for the one-membership-product-per-cart warning in PMPro WooCommerce.
 * Add this code to a custom plugin. https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_gettext_pmprowc_changes( $translated_text, $text, $domain ) {
	if( $domain == "pmpro-woocommerce" && $text == "You may only add one membership to your %scart%s." ) {
		$translated_text = "Include the %stwo percent-s strings%s, which will add the start and end a tags.";
	}
	
	return $translated_text;
}
add_filter('gettext', 'my_gettext_pmprowc_changes', 10, 3);