Yeah, the cool thing about API keys is that you load up a certain amount up front, and you use it when you need. As opposed to a subscription where you pay a fixed fee every month regardless of how much (or little) you use it.

You don't need to pay $10 either - you can choose. $5, $10, $50, whatever. However much you charge your api key, you'll get that amount of tokens worth. This is sort of the semi-hidden way to gain access to premium models for much cheaper

In my case, I paid $30 many months ago. Since then I've done literally thousands of summaries + the whole snake game. I still have only spent like half of it I think (don't quote me on the exact numbers -- the point is it's much cheaper than a subscription)