Haha, that discussion gets quite absurd.
Anyway, as simple and good as the idea is - to use GUIDs as keys - I'd also think of two more concerns:
Legal conditions and customer service.
I think as a single developer you won't stand the obligations of data privacy, protection, security, and international variations about such laws. A solution could be to let some third party distribute your software as a contracted dealer, reseller, or such.
And to decouple you from attacks on your own licensing system, I'd also take the advice people pointed out there to use a license management service. I can't recommend something myself, as I'm just developing for internal use in a company, but googling I see several service providers for the purely technical aspect also covering a bit of making customer support easier:
These results are random and I can't recommend something, but you get a feeling of the offerings and can compare them to others.
One thing is for sure: You won't find something integrating directly into your EXE, at best something that works offline but only within the setup, for everything in the direction of checking license at each start you will need to roll your own, look for things others posted or better look for an online service http based (REST) API. Because that's what you also can do from any desktop application via WinInet, WinHTTP, or several ActiveX or COM classes Windows offers to provide the typical Browser/Javascript httprequest.
Chriss
