MemberPress: Restrict Purchase of a Specific Membership Based on Existing Subscriptions

add_filter( 'mepr-can-you-buy-me-override', function( $override, $product ) {

  // Check if the user is on the MemberPress Account page

  if ( !is_page( 'account' ) ) {

    return $override;

  }

  // Get the current user and their active memberships

  $user = MeprUtils::get_currentuserinfo();

  $products = $user->active_product_subscriptions( 'ids' ); // Get all active membership IDs

  // Define the list of allowed memberships

  $allowed_products = array( 123, 456 );

  // Check if the user has any of the allowed memberships and the product ID matches the restricted product

  foreach ( $allowed_products as $allowed_product ) {

    if ( in_array( $allowed_product, $products ) && $product->ID == 789 ) {

      return false; // Prevent the purchase

    }

  }

  return $override; // Return the original override status if conditions are not met

}, 10, 2 );