How to restrict a client to install a web application for only one domain

Question

I have a product(Web Application), 5-10 clients are asking same application to install in their own domain. i don't have any problem to install, but some clients(who is having technical knowledge) are installing in 2, 3 domains without paying for me. How can i restrict them for only one domain. I mean some authentication process we have to follow, which gives access to clients to install.

could anyone give me any suggestions.

Thanks.

Answer 1

Make a function that sends a request to your server, in example:

 function checkSerial($serial = '1111-1111-1111-1111') {
       $server = file_get_contents('http://server.your-domain.com');
       if (json_decode($server)) { 
             $result = json_decode($server);
             if ($result[0] == 'valid') return true; else return false
       } else return false;
 }

and something on server side (index.php):

 if (isset($_GET['serial'])) { 
       if ($_SERVER['REMOTE_ADDR'] == '127.0.0.1' && !empty($_GET['serial']) && $_GET['serial'] == '1111-1111-1111-1111-')) {
       $result = array('valid');
       } else $result = array('invalid');
 } else $result = array('invalid');
 echo json_encode($result);

This is just a quick demo how you can implement such a thing!