pmprosed-extend-expiration-date-from-set-date.php

<?php
/**
 * Extend the expiration date from a set date for the Set Expiration Date Add On.
 *
 * 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_pmprosed_extend_expiration_date_from_set_date( $set_date ) {
	// Set from date month and day here.
	$extend_from_month = 9; // Set the numerical month from which the expiration date should be extended.
	$extend_from_day   = 1; // Set the day from which the expiration date should be extended.
	
	// Build the extend from date.
	$current_year      = date( 'Y' ); // Get the current year.
	$extent_from_date  = strtotime( $current_year . '-' . $extend_from_month . '-' . $extend_from_day ); // Get timestamp.

	// Check if we're in the extend period.
	if ( time() >= $extent_from_date ) {
		$set_date = date( 'Y-m-d', strtotime( '+1 year', strtotime( $set_date ) ) ); // Extend the expiration date by one year.
	}

	return $set_date;
}
add_filter( 'pmprosed_expiration_date', 'my_pmprosed_extend_expiration_date_from_set_date' );