I have exactly the same problem as wstewart. When I recently updated to the latest version of Limewire I lost my Pro Status. I tried updating back to Pro but Limewire would not recognise my Email address. I have only ever used the one email address. I have been using Limewire for about 2 years and paid for Pro some time ago (about $29.95 Australian)
Like wstewart I was given a number to enter to activate Pro.
Now I am in a quandary with Limewire not recognising my email address and, apparantly, no other way of contacting them. It seems that I have to wave goodbye to my money. Not a very satisfactory state of affairs for an otherwise excellent program.