I have the free Avast and was unable to re-register till today. My old version expired on 7-1-2010 and the new version was good till 9-1-2010. A box popped up this morning to let me know I had 13 days left so all I had to do was fill in my name, e-mail addy and it is now registered for another year. It was very simpleā¦Thanks Avast!!!
Yes it is simple and as mentioned the ability to re-register is triggered by the update notification.
Glad that you now have peace of mind.