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 wasn't introduced too long ago, so if you have 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.