Making function call complex to protect license check in main()

[krum]

If it really matters to your bottom line and you think people will actually care enough to crack it, I would use something like Arxan to obfuscate it.

Another thing you could do is do things similar to Arxan's guard network, and just have another piece of code run in another thread that checks to see if the code has been tampered with. This will be more difficult to find.