I hope this teaches you a lesson. Hiding code.. tsk tsk.
Now, Kerckhoff is a cryptology guy- but all of this deals with security.
Security.. people misunderstand what that means.. so much. Security is not just safety from malicious attackers.
I understand releasing this program this way- solved the problem at the time. But you know there's another way of doing it. There's always another way.
Maybe the software could have been written completely free- and maybe via some mechanism- when it runs- it asks for some permission token or piece of data from a remote server- and then.. with that- proceeds to do what you need. Who knows.
Of course the obvious question everyone is asking- is why was the source not in version control? Maybe you're the first one who asked this question at this point.
I hope you may be inspired to look at other ways of solving this problem in the future. If you're concerned with the authorities- you know.. the boss.. they just want the stuff to work- so they can worry about their own tasks.