These are fake key generators that display a working key (which fails validation) while silently installing a backdoor. Real-world examples have been linked to password stealers targeting browser-stored credentials and cryptocurrency wallets.
You might find text files or Gists containing keys that were valid years ago. These are almost always blocked by Scooter Software’s online validation system, rendering the software unregistered or disabling features after a short grace period. beyond compare 4 license key github