They make agreements with the publishers and SetApp delivers the app updates (usually the same day as the regular app updates are released). SetApp lets you have a certain number of “active” machines. My account (which I got whenever it launched) let’s me have 5 machines but the standard plan might be 2, I’m unsure. Any annual upgrade terms don’t apply, your access is predicated on having a SetApp subscription. So for an app like Ulysses, I don’t have to pay the annual IAP or subscription (the Ulysses subscription extends to iOS too fwiw although other apps like Screens still have their own separate iOS apps, which makes sense).

I actually discovered TablesPlus thorough SetApp and liked it enough to buy the Windows version for the times I use Windows.

There are a number of apps in SetApp I’ve already paid for, but talking to a friend who is a SetApp author, if I install the SetApp version, that actually helps him get paid more so when I do have overlap, I install the SetApp version.

(My friend makes decent money off of SetApp which made me feel a lot better about the whole thing and feel comfortable it wasn’t predatory towards indie app makers).