The expiration date is coming from the unlocking keys BUT the expiration date itself can't lock them up. It has to pull the new keys that exclude PR mod to lock them up. That's why it doesn't lock up until the next time it goes to reach out to the Sage server after 4/30. Obviously it would also lock up if someone manually enters the updated keys. I saw the Evernote post that lists what versions are doing the auto-update of keys: 2015.5+, 2016.2+, 2017.0+.