add_filter('pmpro_payment_option_fields', array('PMProGateway_check', 'pmpro_payment_option_fields'), 10, 2);add_filter('pmpro_payment_option_fields', array('PMProGateway_check', 'pmpro_payment_option_fields'), 10, 2); Source File: https://github.com/strangerstudios/paid-memberships-pro/blob/master/classes/gateways/class.pmprogateway/check.php View in Source Code