1st thing to do is ensure your paid for it at the official site & not elsewhere:
Membership? - **WARNING**- Download p2p Clients ONLY Thru Official Sites (click on link)
If you're sure about that then see
Paying For Limewire Pro ie: send a pm to mformel.
BTW you should receive an email from customer support of LW with a link to your personal pro downld page. Initially you'd get an email in response to your payment. So check your junkmail box to be sure it wasn't sent.