I don’t see anywhere that mentions if this is ad-supported or not.
Most of ours are. We call it out if they’re not.
Most say the ads are not intrusive - it’s on the sleep/wake screen.
Yeah… the only place you see “ads” are at the very bottom of the Library screen or on the sleeping screen. The ads do not show at all in the book you’re reading itself and, honestly, unless you look for the “ad” (which is 99.999% of the time just a book you might be interested in) is if you are actively looking for it.
As someone who uses uBlock Origin, YouTube AdBlock and every other adblock known to man, this is the one place even I would recommend you not waste the money on the “ad-free” experience.
You can get rid of the ad on the unlock by going in settings and having it display the last book opened.