Played through the game twice and couldn't find it. Any idea where it is?

add trading cards

Just revealed it and it says it's already been used, Have you invalidated keys ?

when ever i enter the second building I get stuck and I can't move any ideas?

GMPL-WZN64-4F38 First level of the key is between 5 and 7, while the final level of the key is between K and M