bvarnadoe: I started the game, and entered the serial number listed on my account, but the game says that is the incorrect number.
Don't copy-paste the key, but type it in manually. Otherwise you often copy invisible characters, resulting in pasting an invalid key.
jrbrockm: ... why the game continues to ask me for the serial number every time I launch the game. Yes, I know where to find it on my account, but I don't want to enter it every time I play. Solution?
The cause could be, that the key can't be saved after you've entered it. This has usually to do with missing write permission of the actual user, whether to a file or the registry. Try running the game as administrator once or give your current user account full read-write access to the game's directory and subfolders.
