Deactivate Your Primary Console
When you first set up your PS4, whenever you bought it, you’ll have been asked if you wanted to activate the system as your Primary Console. While you were right to do exactly that at the time, it’s important to deactivate this before moving onto a new system, be it a Pro or just a Slim. Activating a system as your primary console allows any other account on the PS4 to use apps you purchase from the PlayStation Store, enjoy the benefits of your PlayStation Plus subscription, and a few other bits and pieces. Essentially, it allows you to share all your content with any other user on the system. However, you can only activate one system as your primary console.
Therefore, before you head out to pick up your Pro, it’s important to deactivate your old PS4, whatever you decide to do with it. It’ll save you a lot of headaches in the long run. If you’re planning to do the system data transfer, however, you won’t have to worry about this as the process will ask you which one you want to make your primary system.