First of all, I have to tell you that you were scammed if you paid for a 'life membership'

LW basic is free.

LW Pro costs $21.95 for 6 months of email support & free updates or $34.95 for 12 months of email support & free updates. Sometimes there's an offer of Pro for $13.95 for a one-off download with no updates & no support,
The only official site for download (shows on your CC statement as payment to LimeWireLLC) is: Lime Wire » Download LimeWire

There is no lifetime subscription. LW has never cost more than $34.95 from the official site. Scam sites are the ones who charge heaps & offer bogus lifetime memberships.
If you paid a scam site for Pro then you won't ever be able to update from the official site.
Membership? - **WARNING ** BEWARE** - Download p2p Clients ONLY Thru Official Sites

If you're seeing the license error, check out this thread (click on link): Somebody Help Me Please! (I Get A Message Saying Limewire Cant Find A License For This File)