I friend told me about a site that has 50 avast keys. I checked it out for myself. There are FIFTY different keys for various versions of avast! I figure avast may want to know about it. I know I would if I were them.
Possibly an e-mail to sales @ avast.com
(I am not absolutely sure, but it seems like a good place to start, and it wouldn’t hurt.)
Hi,
Avast.com and find the Contact/Support Link. Usually it is on the menu on the home page.
Contact a Forum moderator, hopefully someone will see this post.
Karl
When the next update comes out, these keys wouln’t be valid any more. 
I hope so… but at other times, this did not happen… I can’t imagine why they don’t blacklist immediatly these kind of keys… 