I am not entirely sure I am understanding you, so I'll just explain how you do the registration. If you're already in the game in Steam and it doesn't say trial mode, then you should be good to go.
1. Open the game. A window asking for your license key will pop up. This is for the base game. If no such window pops up, then you've already registered it.
2. Go to settings, expansions, and there will be a list of expansions (just the one right now). Click the link for it, and it will give you a box to register the expansion. If it says that is already unlocked, then you've already registered that one, too.
By "registering," that's not sending data to us or Steam, it's just entering your license key into the game. So no worries! The expansion is not a separate runtime, but rather adds its content right into the main game itself (Steam treats it as "DLC" on the games menu).
Hope that helps!
