If I bought the retail version, is the serial key stored in my redist folder or DVD ?

[Statyk]

That's odd. Maybe check your email?

He got it through retail, which means in a store, not online. Therefore, there'd be no email.

EDIT: Go to "C:/Users/YOURUSERNAME/My Documents/Amnesia" And check if there's a file labelled "installkey". If it's there, open it in notepad and it should have your serial number inside. Copy and paste it where specified for Justine.