Go to your email folder & look for your email from customer/sales support & open it & see if the link is still valid. Remember if you paid for 6 months & that length of time has passed then your name will have been removed from their database. Another way to check is go here Lime Wire » Support & click on the Download/Update LimeWire PRO link.

If you purchased PRO LESS THAN 6 months ago then send a PM to limenathan (click on link)