Prevent script for sinle domain

I have developed a script for my client, he asked me for the source code but i want to
set the validation to use the script for single domain only. A client should not b able to run another copy of that script without prior notice.

 

if ($_SERVER['HTTP_HOST'] != "www.allowed.com")
{
    header("Location: http://www.google.lv");
}

PHP:

 

Thanks but it can be easily edited by the client. As i described he wants the source code. Any other solution??????

 

Set up a simple script on your end that just outputs www.allowed.com as text. Then you would call that script from his tool and check the result (with curl). If the result is not the same as the current domain the tool is hosted on than use something like die(); or else don't do anything. Now just encode this part of the code in his script and put in some global variables that are needed for the script to run. That way if he deletes this code the script won't work.

Hope you understand what I mean

Thanks

 

Encode it ( Zend, .. ).

 

Without encoding?