If you “export” the chat history from your standard chatGPT account (all those questions stored on the left). You will see in the JSON output ID’s for sessions and questions (and re-questions etc). That indicates to me that the session is being stored somewhere as the chat takes place. I don’t keep any history in my chat sessions and they seem to respond the same way as when the first models came out (and then I did throw back up the whole history).