How long since you paid for it? If it's still within 6 months, Go here:
http://sales.limewire.com/support/pro_lookup.php, and enter the e-mail you used to purchase it with and it'll take you to your personal download page.
If it's past 6 months, you'll need to purchase it again or download the Basic(Free) version:
http://www.limewire.com/english/content/download.shtml