I do not consider this to be an upgrade. An upgrade would be like actually changing one part for a new improved one. This may be a physical part or new operating system. But when everything has been purchased, already paid for, and in place, then it becomes an unethical practice of extortion rather than a subscription for a service. Suppose I built you a house and you paid me in full for it. Then I told you if you ever need more storage space I would charge you a monthly subscription fee to give you access to your own basement by remotely unlocking your basement door, would you stand for that?