One, if you charge above API costs, you should never police usage (so long as you're transparent with customers). Why would you need to cap usage if you're pricing correctly? (Rate limits aside)
Two, yes, many people will pay $20/mo for ChatGPT and then also pay for a product that under the hood uses OpenAI API. If you're worried about your product's value not being differentiated from ChatGPT, I'd say you have a product problem moreso than OpenAI has a billing model problem.
Two, yes, many people will pay $20/mo for ChatGPT and then also pay for a product that under the hood uses OpenAI API. If you're worried about your product's value not being differentiated from ChatGPT, I'd say you have a product problem moreso than OpenAI has a billing model problem.