How long are ChatGPT/DALL-E3 chats & images saved for in your chat history?

How long are chats from ChatGPT, in particular Dall-e3 generated images saved for per user?
I have downloaded almost all the generated images I like, but I feel like I want to go back and explore some of these with variations in the future. But if there is a limited storage time, then it would be good to know before I log in one day and they are gone!

Note: I notice in my ChatGPT3.5, I have stored chats going back to January 2023.