Pre-order has nothing to do with 30 free days - that's included for everyone. What platform and version you have? E.g. PS3 or PC and physical copy or Digital Download? Either way - what have you registered was the early acces code. You need to register the main game code which in case of physical copy is on the voucher in the game box and in case of digital download would be emailed to you. Check also your SPAM folder. In case of PC version you need to redeem code via Mogstation in case of PS3 via PSN / PS3.