There is no membership, only 6 months of free upgrades for 18.88 (pro version). Seems to me you have bought something at scam site
Please say where you saw that, you've been had! Now be more conscious of your purchases next time...
Ciao
Edit: Prices as of 2008-9 are: Lime Wire » Download LimeWire _ Pro for 6 months support $21.95;
_ Extended Pro support lasting 12 months for $34.95 __ LimeWire occasionally offer specials such as $13.95 with no support or updates, just a single copy of LW Pro.