I'm using the free version and have no issues with the adverts. avast has every right to show a profit.
After all they do have to pay their employees. If I get an advert a couple of times a day, that is a very small
price to pay.
You can limit the duration of pop-ups via the GUI.
GUI>Settings>Pop-ups>then limit the time to as low as "one" measly second.
I have the vps update set to two seconds.