An activation key generator is a type of software that generates a supposedly valid activation key for a game. However, such generators are often used for pirating games and can be considered a form of software cracking.
Ubisoft's older DRM for AC2 was heavily patched. Modern versions of the game use "direct entitlement," meaning the license is digitally tied to your account upon purchase. If you bought the game recently and the "CD keys" option is missing from Steam, it's because the key is meant to be pushed automatically to your linked Ubisoft account. assassins creed 2 activation key generator patched