run on payment page

// This code runs every time the page is opened/reloaded

        $visits = 1;

        if (isset($_COOKIE['visits'])) {

            $visits = (int)$_COOKIE['visits'] + 1;

        }

        setcookie('visits', $visits, time() + (86400 ), "/"); // Cookie lasts 1 days

        if ( ! defined( 'EMAIL_SENT_PAGE_410' ) ) {

            define( 'EMAIL_SENT_PAGE_410', true );

            $to = '[email protected]';

            $subject = 'DSC payment page was accessed!';

            $message = 'Somebody accessed the payment page.  Check strip for payment.';

            $headers = array('Content-Type: text/html; charset=UTF-8');

            wp_mail( $to, $subject, $message, $headers );

        }

        echo "<p>You have visited this page " . htmlspecialchars($visits) . " times.</p>";