A local licencing system?

If it is an open source licence just include it in your software files and state the licence before download. If it is a commercial licence you will need to generate some sort of authentication key on purchase otherwise it would be useless.

This might be useful.
https://help.github.com/articles/open-source-licensing/

For commercial licencing it would well be worth paying for a service provider to do all the locking and checking for you. (e.g. http://www.nalpeiron.com/)

Best wishes,

Paul.