After you pay to become a pro member your web browser is sent to a page you are told to bookmark or save for 6 months since you apparently do not have this you can go to the page listed below and enter the email address you gave when you first downloaded your version and they will email it back to you then you could get the latest version for up to 6 months from when it was purchased according to my understanding
If you never got the pro paid version then I only know that they are asking people who have older versions to update to improve the service for everyone good luck !
http://www.limewire.com/index.jsp/supportpro