The ads in my avast! arent changed is it same for all ? As internet security 5.0 is not anymore 50 % off as i can see by the “News” on website and the price. Its only 25 %. So i hope you did not missed it ? 
Well, I see different one… presumably locale/country dependent? (Though, same one if I switch to English).
The in-product banner is definitely locale-dependent, and even with the same locale, different people may be seeing different banners as some A/B testing may be in progress…