Only allow shipping to specific Zip Codes for Paid Memberships Pro Shipping.

my-pmpro-valid-shipping-zip-codes.php

<?php
/**
 * This will only allow users to checkout with specific zip codes for the Shipping Add On for Paid Memberships Pro.
 * You will need to use this code recipe together with the PMPro Shipping Address Add On - https://www.paidmembershipspro.com/add-ons/shipping-address-membership-checkout/
 * Add the code below to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
 
 
 function my_pmpro_valid_zip_codes( $pmpro_continue_registration ) {

  // Check if things aren't okay, if not, lets not run this code further.
  if( ! $pmpro_continue_registration ) {
    return $pmpro_continue_registration;
  }

  $valid_zip_codes = array( '1234', '5678', '1448' ); // Create an array of zip codes that are valid.

  // Check if the shipping zipcode is valid.
  $shipping_zip_code = $_REQUEST['szipcode'];

  // If it's not valid, stop registration and show an error.
  if ( ! in_array( $shipping_zip_code, $valid_zip_codes ) ) {
    pmpro_setMessage("Sorry, we do not ship to that area. Please choose an alternative address.", "pmpro_error");
    $pmpro_continue_registration = false;
  } else {
    $pmpro_continue_registration = true;
  }

  return $pmpro_continue_registration;
}
add_filter( 'pmpro_registration_checks', 'my_pmpro_valid_zip_codes' );

This recipe is included in the blog post on "Restrict your membership sites shipping locations by specifying valid zip codes." at Paid Memberships Pro here: https://www.paidmembershipspro.com/restrict-your-membership-sites-shipping-locations-by-specifying-valid-zip-codes/