If you bought pro then you would have been sent an email with a link to your personal pro downld page. Most people bookmark this page. Did you?
Pro offers 6 months of updates. But if it's now more than 6 mths since you purchased pro then you can't get more updates & your name is taken off the list. For a very limited time after the 6 mths they offer a discounted pro. But you need to be quick.
When did you purchase pro? And did you get it here: http://www.limewire.com/english/content/download.shtml