lp-basic-shipping-state-validate.php

<?php

add_filter('leaky_paywall_basic_shipping_validation', 'zeen_ignore_state_for_international', 10, 2);

function zeen_ignore_state_for_international($errors, $fields)
{

    // if the user selects GB (Great Britian), then remove the state validation
    if ($fields['country'] == 'GB') {
        unset($errors['state_empty']);
    }

    return $errors;
}

add_action('wp_footer', 'zeen_remove_state_field');

function zeen_remove_state_field()
{
    // if the country selected is GB (Great Britian), then remove the state field
?>

    <script>
        (function($) {

            $(document).ready(function() {

                $('#country').change(function() {
                    country = this.value;

                    if (country == 'GB') {
                        $('.state-field').hide();
                    } else {
                        $('.state-field').show();
                    }
                });
            });

        })(jQuery);
    </script>
<?php
}