Serial Number needed?

[mrgame44]

So I recently had to reset my PC, and I wanted to go back and play Amnesia. However when i went to play it, it says to enter a serial number. If i ever got a serial number i no longer have it. I would very much prefer to be able to play the game i payed for, any help would be appreciated.

[Kreekakon]

Apply the latest update (v1.3) which can be found HERE.

After update v1.2.1 the game has no protection so the key is not needed anymore.