How long ago did you buy Pro?
Who did you pay for Pro?
If you bought from the official site Lime Wire » Official Website & Free Download, BitTorrent « are your Pro benefits still current? If you bought 6 months worth of Pro, it needs to be less than 6 months since you paid...the yearly Pro deal was introduced less than a year ago, so if you bought extended Pro then you should still be within the timeframe.

If you did buy from the official site & are still within your Pro timeframe, go to this page & try all email addresses that you might've used.
Lime Wire » LimeWire PRO Support Center

If you did buy from the official site but your Pro benefits have expired...you can't download a new Pro installer. If you didn't buy from the official site then your email address would never have been in the official database & you can't download a new Pro installer.