Quick account question - please help.Follow

I just picked up the Mines of Moria expansion that comes with the full game and the expansion. I already have an account with pre order bonuses from the original game. My question is...

If I enter the product code on an existing account, will I get the 30 days free? Or do I have to make a new account? I want the free 30 days (obviously) but really don't want to lose the pre order bonuses I got when the game came out.

Thanks.