ChatGPT can now look at past conversations you have had with it and reference them in its responses. When you start new conversations, ChatGPT may recall past conversations you have had with it, in addition to things it has remembered about you in Memory to provide more helpful, contextualized, and better answers to your questions.
You are always in control of what ChatGPT knows about you. You can delete specific memories in Settings, you can delete past conversations from your conversation history, or you can archive conversations to prevent ChatGPT from remembering them.
But remember, turning Memory off does not clear your memories, and deleting a past conversation does not erase memories remembered from that chat.
If you would like to have a conversation without any Memory - you can turn Memory off in Settings or use a Temporary Chat.