I’m looking to change my reading and buying habits away from Amazon and need an alternate source for my ebooks. Where can I buy ebooks that won’t expire or have their licence revoked and will allow me to download a copy of that ebook I can store on my own system regardless of the websites status?
I’m operating under the (perhaps mistaken) assumption that OP wants to “buy” an e-book in part to support those responsible for making it. And of course you can’t support an editor or cover designer or publicist directly, but they do get paid indirectly because books get sold.