Aside from really disliking subscription models, which the app forces the upgrade as instead of making the lifetime option at all apparent, these FAQ questions are where I was most confused before reading.
It's not made clear that Pro =/= Premium at any point. Unless I'm missing something, Premium isn't mentioned at any step at the moment when clicking through from the big red advert at the top of the app (which really needs an option to be turned off). It just takes you to a in app page about breach monitoring, no mention of premium. Clicking learn more takes you to a webpage about breach monitoring, again zero mention of premium. Clicking continue back at the in-app breach monitoring page takes you to the subscription only "Offer for Pro Users" page, which yet again has no mention of a distinction between pro and premium or that there actually is one time purchase option...