I have been using a .exe I had developed for myself a while back, and I'd like to start licensing it to some clients, however the original developer is not available to add a licensing solution to the app for me.

Is there anyway I can do this myself with some sort of off the shelf solution, or is there anyone here, who would be interested in tackling this?

I don't need it to be locked down like fort knox, really I just need a simple licensing system, and it can be done manually, where I would create the licenses myself for now.

I am just looking for a simple solution that I could use that won't cost an arm and a leg.

Any insight would be appreciated, thanks!