The API charges are only for apps that make a lot of requests in a short time. A single user shouldn’t exceed the free allowance in normal browsing but three of four users sharing an API key almost certainly will if using it at the same time.

I remember seeing Jet play at Leeds festival years ago. Some girl in front of us doing this, until a pint flew across the crowd and hit her lower back, splashing upward. Couldn’t have got more of that liquid on her if you’d tried. We were close enough to get a bit of the spray but it was worth it to hear her as she looked down at her partner and murmured “that was warm…”