Hacking Yifan Lu says Register for PSM

[psvpwner]

Right, I know how to get it on the vita, but I'm just wondering at the end of the month will it still be in my pan download list, or purged out. (Even though there's no expiration date)

Most likely Sony will delete it from the store and everyone's download lists the next few days. The expiration date field is probably just there for PSN+ games that you have for a limited time only. I can't see it having anything to do with how Sony decides to permanently remove something from their store.