If you bought Pro from the official site Lime Wire » Official Website & Free Download, BitTorrent « (payment to Limewire LLC), you'll recieve an email with a link to your Pro personal download page. If that's the email that you're talking about...bookmark that link, that's what you use to download Pro installers during the 6 months/year that you bought Pro for

Once you've bought Pro, you can download as many installers as you like (say if you have multiple computers & want to use Pro on them all)