Have you looked in the avast settings, I don't know if it is in the Privacy settings now about showing other avast products (or wording to that effect).
It has changed recently and the option doesn't exist in the avast free version (which I use), so I can't be more precise.
EDIT: Sorry I have noticed that you have posted this in the Avast Mobile Security for Android forum. Can you clarify where you are seeing these ads/promotions ?
If as I suspect it is in the Avast Premier, then this should have been in the Avast Free Antivirus / Pro Antivirus / Internet Security/ Premier forum.