Best place to hide a key in the Windows Registry?

Question

My Delphi program has a built-in protection mechanism to check for banned license keys on the Internet and displays a message to the user if a blacklisted key is found.

Answer 1

If you really want to go that way, hash or encrypt the keys and then check the hashed or encrypted user key to those on the registry.

Be sure to check if there's any keys in the registry to be sure if the user didn't erased them.