Show checkout time for Paid Memberships Pro invoices.

pmpro_show_time_on_invoice.php

<?php
/**
 * Show the time of checkout on Paid Memberships Pro Invoices.
 * Add this code to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 * See date parameters available to adjust time/date - http://php.net/manual/en/function.date.php#refsect1-function.date-parameters
 * www.paidmembershipspro.com
 */
 
 function pmpro_time_for_invoice( $invoice ) {
     echo '<li><strong>Time of Checkout: </strong>' . date_i18n( "H:i", $invoice->timestamp ) . '</li>';
 }

add_action( 'pmpro_invoice_bullets_top', 'pmpro_time_for_invoice' );