From personal anecdotal experience: chatting for hours would cost the company a few cents. In our company, developers are encouraged to try it out, and there are a few projects that use it a lot. The user with the highest cost has been using it in a loop, with minimal human intervention (and hence downtime), and it cost the company 2000 bucks for a month.

With “normal” use, even extensive, it’s very hard to go above 50 bucks.

I don’t know the company’s agreement with the provider - I’m guessing this is on top of a subscription cost - but either way if you want to make a real dent just chatting isn’t going to do it.