You'll only be able to redownload Pro if you paid less than 6 months ago (remember, you're covered for 6 months of updates). If that's the case you can just download from your Pro download page. If you didn't keep the link, go here & enter the email address you used to buy Pro
http://sales.limewire.com/support/pro_lookup.php

Let us know if you run into problems

*It's always a good idea to back up your Pro installer, just in case!