Registration Code

[Math]

Hello,

I wonder if I can ask this particular question here...
I'm writing this piece of Python Software and I'm almost done...:-)
But now I want the end-user to register this software with a registration 
code or perhaps something like an evaluation demo version which expires 
after some period of time...
Is this the right place to ask or does anybody know where to look for more 
on the subject?

Thanks