Clue on conversation "history"-- "While ChatGPT is able to remember what the user has said earlier in the conversation, there is a limit to how much information it can retain. The model is able to reference up to approximately 3000 words (or 4000 tokens) from the current conversation - any information beyond that is not stored.

Please note that ChatGPT is not able to access past conversations to inform its responses."

https://help.openai.com/en/articles/6787051-does-chatgpt-rem...

Some interesting techniques I've seen involve essentially a ring-buffer and after each turn a call is made to summarize the conversation up to that point and use that as context for subsequent prompt