What is an easy way to turn that page into a paid service?

Something like this would be perfect:

    <?php

    $token = $_GET['token'];

    if (file_get_contents("https://stripe.com/check?token=$token")!='ok')
        die("Please pay first: https://www.stripe.com/pay?domain=mysite.com");

    # User has paid .. let's do the work ...

But I guess nothing as simple as this exists? If not, what is the closest?