Yes, there will be an actual product code that you have to enter for the digital PC version. If you ordered from the Square Enix store, then you will see it under -> Account Management -> Orders -> View Specific Order. It is where you got the preorder code from. However, it will not be there until the actual release date. The preorder code only allows early access until the 27th, and then you have to enter the real product code to continue playing.

If you ordered digitally from somewhere else like Amazon, then Amazon will email you the final product code usually or list it in the order download area upon actual release date.