Paul :

Very similar to what you said in your previous post. There would have to be a separate Registry Key for each installation.

Reminds me of previous times when software was sent via 'floppy' disk. Each disk had a unique installation/registration code.
If the purchaser shared the software with others then of course the registration code wasn't worth much. That would be the
same thing here when the user receives the hashed registration code.

All in all its just an additional step to slow down the devious minded. Honest folks will be kept honest with the registration key.
And then there are those who like to tinker with the VBA code. That cannot be protected no matter what you do. If the user
knows enough ... the code will get broken.