Create License system for Windows Application

Hello,

Does someone know or have information how to build License system for our windows application projects that contains:

- License Generate

- License Edit

- Encryption

- Offline Activation (by file or code)

Where admin create some keys, and when user register the software to use it (not every time when start to ask for registration again, must store results)

I'm looking for something like this but cannot find a simply and stable method, does anybody knows?