If I wanted to have a conversation about it, and you wanted to charge me a flat fee per utterance on the basis that you had to reread the text anew every time, I wouldn't be paying you at all.
If we were having such conversation via e-mail/IM and I learned that you're just asking me questions one by one in your replies, questions which you could've easily included in your first e-mail - then believe me when I say it, I would charge you the same way OpenAI does, and I'd throw in an extra 50% fee for being inconsiderate and not knowing how to communicate effectively.