You could also use machine vision + AI to detect what books are there, based on the writing on the spine. If they're tagged with an ISBN number, even better.
That's basically what Amazon Go does, but with a wider set of items. Your problem set is simpler, since you’re only recognizing books and text.
Using a visual method has the additional bonus of showing ...
Gustavo, welcome to the board! Your idea of using RFID tags is a good one, so don't get discouraged quite so easily.
Many RFID systems are very short range, but they are designed for that purpose. RFID readers with longer range are certainly available. For example, many libraries have RFID "antennas" (actually coils) on each side of the entrance ...
Theoretically, yes. Practically, you'll have to design a complete NFC frontend to drive a coil that's ca 1m in diameter. NFC isn't really designed with that degree of impedance mismatch in mind, so chances are the tag itself would need to be modified, too. So, not really NFC compliant afterwards.
So, no. The N in NFC is for "near".