True, you'll lose them. BUT, if you just go in and buy books that you have an interest in, but no time to read right now, you can use up your credits quickly. And even once you stop your membership, you still have access to the books you've bought. Buy a bunch of the Royal Spyness books, you like those. Or, how about a Phryne Fisher book. Start with
Cocaine Blues . And you could try the Mary Russel/Sherlock Holmes series, by Laurie King. Start with
The Beekeeper's Apprentice.
Just go ahead and stockpile some books. Then drop the membership, and rejoin when you run out of stuff to read. Or decide you really, really want something that just came out.