Limit MemberPress Signups to one Country

mepr-limit-signups-by-country.php

<?php
function limit_signups_to_one_country($errors) {
  // Limit Signups to USA only
  if(!isset($_POST['mepr-address-country']) || $_POST['mepr-address-country'] != 'US') {
    $errors[] = 'Sorry, signups are currently limited to USA only.';
  }
  
  return $errors;
}
add_filter('mepr-validate-signup', 'limit_signups_to_one_country');

Multiple countries example

function limit_signups_to_one_country($errors) {
  $countries = array('AU', 'NZ');

  // Limit Signups to USA only
  if(!isset($_POST['mepr-address-country']) || !in_array($_POST['mepr-address-country'], $countries)) {
    $errors[] = 'Sorry, signups are currently limited to Australia and New Zeland only.';
  }

  return $errors;
}
add_filter('mepr-validate-signup', 'limit_signups_to_one_country');```

Removes countries from dropdown itself.

function filter_out_countries($countries, $prioritize_my_country) {
  $countries_to_keep = array('AU', 'NZ');

  foreach($countries as $code => $title) {
    if( ! in_array($code, $countries_to_keep) ) {
      unset($countries[$code]);
    }
  }

  return $countries;
}
add_filter('mepr_countries', 'filter_out_countries', 11, 2);