blacklist. Users with this key would see desktop "nag" notifications stating their software was not genuine and were blocked from downloading certain updates from the Microsoft Download Center. Service Pack Blocking:

Keys tied to specific hardware builders like Dell, HP, or Lenovo. These are usually found on a physical sticker on the computer chassis.

Legally, Microsoft still owns the rights to Windows XP. Using a key found online is generally considered software piracy, as legitimate keys were meant to be purchased or obtained via a Certificate of Authenticity (COA) sticker on your hardware. How to Find Your Original Key