You will be able to use any version you paid for. I am one of those "Crazy people" who have bought and have access to all systems (just in case). Make sure you add the code to your existing account. When done correctly it will show up in the Mog Station.

Just remember that your hotbars and UI will have to be completely reset on each system. They will not be there when you switch systems so having access just means you can log on. However for me since I am normally on PC and I don't want to travel with a bulky case, I just take my PS4 and take a little time setting up when I get to my travel location.

Below is what it will look like when you have access to different systems.