Can you not add him to your family library? That's what it's there for. He will need a compatible device though. A $50 Fire tablet will work. He will also need to open a Amazon account but it's free to do so. The family library allows one extra adult account. I have my hubby on mine and no you don't need Prime.
https://www.amazon.com/gp/help/custo...deId=201620400
Sent from my Nexus 7