I know that it says Disposable, but is it possible to use it more than once if its cleaned and maintained? What exactly makes it "disposable"? Does it just have a certain amount of battery life or what?
The product information specifies that the power source is not replaceable - that's probably what it refers to. As a non-vibrating ring, you could probably use it more than once, though I don't know how durable it is. Looks like there's plenty of reviews on it that could give you a more in-depth look.
Essentially what it means is you can't replace the batteries. You CAN however replace the bullet with a more high quality one and get a few more uses out of the ring after the power source dies!