The paid version still has the code to show ads, at least if you paid for it "the old way", i.e. via buying "Pro" activator app. But at this point ads are not activated in the paid version.
(If you think about it, it sounds a bit spooky that something can be remotely activated in the app on your phone, doesn't it? And it is not Halloween yet!)
You brought up an interesting aspect of the ads inclusion. On one hand, I don't see them, as they haven't shown up on the paid app. On another hand, for the most time, I tune them out and don't even notice what's in the ads where they are present.
But yes, - from what I read, there are different "ad networks", with different quality of the content, and the app developers have control which one they choose. My understanding is that with at least some of them, there is also some degree of control of what can and cannot go into the ads. I've seen when the website owners and app developers were taking measures after inappropriate ads showed up and were reported by the users.
I suspect that more scrupulous ad providers might be paying smaller dividends than tabloid-like ones. (And the highest payoffs are probably from the porn-industry.)
By the way, there are 3-4 other threads already about this newest "
ADdition", including this detailed discussion of the situation:
https://www.aqua-mail.com/forum/index.php?topic=6084.0
