Set a custom PMPro Confirmation Message. This example recipe include the ability to customize the confirmation message if the member checked out using the Check payment gateway.

custom-check-gateway-confirmation-message.php

<?php
/**
 * Customize the default confirmation message shown to new members.
 *
 * This recipe also adds a unique custom message if the Check gateway was used at checkout.
 *
 * 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/
 */
// remove the default confirmation text
remove_filter( 'pmpro_confirmation_message', 'pmpro_pmpro_confirmation_message' );

// add new confirmation text
function my_pmpro_custom_confirmation_message( $message ) {
	global $current_user;

	// Set default message.
	$message = '';

	$morder = new MemberOrder();
	$morder->getLastMemberOrder( $current_user->ID, null );

	// Let's check i the last order used the Check gateway and is still pending.
	if ( $morder->status == 'pending' && $morder->gateway == 'check' ) {
		// Add a custom message if user checked out using the Check gateway.
		$message .= '<p>This is a new confirmation message if the Check gateway was used at checkout.</p>';
	} else {
		// Add a custom message if user checked out using any other gateway.
		$message .= '<p>This is a new confirmation message.</p>';
	}

	return $message;

}
// Priority 15 to run after the default confirmation message. Priority must be higher than 10.
add_filter( 'pmpro_confirmation_message', 'my_pmpro_custom_confirmation_message', 15, 1 );