Had you been seeing the prompt to update to the latest LW version? Choosing the option to update will install the latest basic version, regardless of whether Pro or basic was previously installed.

How long ago did you buy Pro? If you bought less than 6 months ago (LW have very recently introduced a 1 year deal for Pro) & paid Limewire LLC for Pro then you should still be able to download a Pro installer. Did you save the link to your Pro personal download page? If so, just follow that. If you haven't saved the link then go here & enter the email address that you used to buy Pro.
Lime Wire » Support

If you bought from a scam site or bought longer than 6 months ago then you'll have to pay again for a Pro installer.
Lime Wire » Official Website & Free Download, BitTorrent «