How to make sure PHP Scripts are only used on one machine by a client?

[Diomedes]

I have a set of PHP scripts sitting on several clients servers and I want to get the mac address for that server so that I can store it and determine that the PHP scripts are not being used on another server.How can I get the Mac address of a computer using PHP somehow?Is there a better way to determine if the PHP scripts are being used on a different machine?Thanks all