Ah, I understand now.
I think anvil is not as well known as it should be, so just in my opinion a freemium model where all they want is for more people to know their product exists, while you get to use all of the world class features with only a tiny few caveats like unlimited run-time for cloud functions is pretty a pretty darn good one.
I used the free service at my job and made about 1/2 a dozen apps for well over a year before I got approval to pay for it, and by that time it was so useful it was definitely worth ~50/mo.
As long as you don’t mind the banner or the subdomain limitations, you can even create an entirely monetized site before ever paying them a penny, which I think is cool.