Execute custom code if the user does not have access to the content.

my_pmpro_has_membership_access.php

<?php
/*
 * Execute custom code if the user does not have access to the content.
 */

$queried_object = get_queried_object();
if ( 
  function_exists( 'pmpro_has_membership_access' ) && 
  ! empty( $queried_object ) &&
  empty( pmpro_has_membership_access( $queried_object->ID, NULL, false ) )
) {
  // Execute custom code here for users without access.

}