When people pre-order and get he early access. We need to put in a special code. Then we get access to the content a week early. But when that week is up, we're barred from the expansion until we have to grab another code to put in.
This has happened for 3.X and 4.X from what I remember.
Is this going to be a thing in 5.X? If so, why can't we just have a one time code that saves the playerbase some hassle?