Stop members from renewing their current membership level [Paid Memberships Pro].

stop-renewing-members.php

<?php
/**
 * Stop members from renewing their current membership level.
 * Add this code to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
 
 function stop_members_from_renewing( $okay ) {
 		
 		// If something else isn't okay, stop from running this code further.
 		if ( ! $okay ) {
 			return $okay;
 		}

 		// If the user doesn't have a membership level carry on with checkout.
 		if ( ! pmpro_hasMembershipLevel() ) {
 			return $okay;
 		}

 		// Check if the user's current membership level is the same for checking out.
 		if ( pmpro_hasMembershipLevel( '2' ) && $_REQUEST['level'] == '2' ) { // Change level ID to a different level.
 			$okay = false;
 			pmpro_setMessage( 'This is your current membership level. Please select a different membership level.', 'pmpro_error' );
 		}
 		return $okay;

} 
add_filter( 'pmpro_registration_checks', 'stop_members_from_renewing', 10, 1 );