Ads are shown when there is content available; from what I’ve seen, it is definitely not a constant stream. We’ve done a lot of testing around ads, and the performance impact isn’t measurable. As for the one-time payment, @Ravenfyre is right, they aren’t sustainable which is why nearly every company has moved away from them. We have ongoing costs and showing ads is a way of making up for some of the expenses.
Then it’s broken on my end, because as soon as one ad is done it automatically plays another one and it’s constant until I close the program and restarting doesn’t fix. It’s just always a constant streaming of ads one after another and right now I’m using it to mess around in Destroy All Humans 2 and I get FPS drops as soon as a new ad loads in which is every 15 seconds.