Thanks, my intention was actually to be as customer-friendly as possible. From my perspective, the customer can walk away whenever they want (they don't even need to unsubscribe), and they have choice for expiry based on their expected usage pattern/accounting department. Obviously I'm wrong though!
Hmm, that's an interesting idea regarding the membership. I'll think about that as an option. Regarding the dollar balance, I didn't like the idea of using dollars and then discounting how much a dollar actually cost someone, since at that point you're effectively using a credit system that happens to be called dollar. But a membership where you get a base number of credits per month/year and then the ability to purchase more as needed (with bulk discounts) could work and I like it!
Thanks for the feedback and the idea of how to fix it!