To me this just looks like it must be stored locally and then called whenever you would would use that id.
Pulls it up and sends the whole conversation again. But not 100% sure
Probably the conversation_ID we see in response is more about openAI being able to check that conversation(api call) for abuse or anything else and have some ID on it. Or you can report something to openAI and mention the ID which they can lookup. Probably also related to “user” we can send