The PS Vita allows only one PlayStation Network account per portable, meaning that if you want to add a different user or use an international account then you’ll need to format the device to be able to do so.
As discovered by a NeoGaf user in a FAQ from a Vita hands-on event, the question regarding the number of accounts per system was answered as follows : “Only 1 account. If you want to to use a different account, you need to format the system to factory settings.”
Gamers didn’t respond well to this, with the heading of the forum topic clearly stating how most felt. However until now we had no confirmation, that is until Sony Japan’s Third-Party Relations spokesperson Brad Douglas, clarified the issue via twitter, pointing out that the PlayStation Portable also limits players to one account. “The only difference is that Vita requires you to do a factory reset when logging into a new account.”
There has been no reason given for this decision.