I have a C++ application which I want to release to a bunch of testers (<10.) I need some simple way to limit those testers from distributing it further. There's no need for super-duper hack-proof protection here, but it should be impossible for normal users to circumvent the protection. I can easily require every user to run some registration application and probably even afford to make one build per tester (though I'd rather like to avoid that.) It would be cool if I could add an time limit, but limiting circulation is definitely enough.
Some open source license managment solution would be great, but what is the easiest way to get some protection running so people don't distribute early access builds? (Not even accidentally, i.e. someone looses his USB-stick or so)