I know it has been designated lifetime because I saw it once when I got partially through the import process and could see my accounts listed in the web wallet, clicking on that account showed it was lifetime. However, all the accounts from that import disappeared the next time I used the web wallet after it stalled loading the claim balance page.
I am tired of my accounts being in limbo, really hoping the devs are able to create soon an import pathway for accounts with lots of keys that doesn't require a computer science degree to use. I was really getting into trading on the DEX in BTS1 and I am looking forward to doing the same in the much improved BTS2 as soon as I can. In the meantime, it is nice to know if that account refers a user it should be given the referral credit.