First of all I know nothing I can do that 100% prevents illegal copying of my software. I'd like to just make it reasonably hard for a competent person to do, and almost impossible for an unknowledgeable person to do.
I have a contract job coming up to develop a web app using the WAMP stack, commissioned by a company's IT manager. During our meeting and conversations, he kept being generic about the software requirements, seemingly refusing to develop requirements specific to his company. So I got the impression as if he was intending to resell the software to other companies for his profit.
And for people who say "people who pirate software aren't in your target market anyway", obviously that doesn't apply in this case because if he resells my software to other companies, those companies ARE in my target market.
The functionality in my software will be divided both in the server-side (PHP) and client-side (JS) using a good JS framework, if possible I want to protect both, (but I think for JS the only thing I can do is obfuscate the code).
I can't just refuse the contract because I need the money.
Is there anything at all I can do?
Edit: I'm also open to using external applications (i.e. written in C, Java, etc. or compiled into dll) to handle the copy-protection. Just need to know the general mechanism of it, if possible.