They do have membership. It’s called a library card. If you don’t return items they will put a Stop on your card.
Unlike a Costco, a library card is free.
I would charge $30 per adult library card and $10 for kids...or $50 for a family card.
At the end of the year all fines and missing items must be accounted for before the “card” is reactivated.
Problem solved.