Chat Transcript API
The Chat Transcript API allows you to retrieve the complete chat history and metadata for a particular conversation by using its unique chatId.
All chats are individually available via a REST API. URL's are sent in dialogue webhooks under the _links.chat field and under _links.self in Handover API events.
You must provide an Authorization header, with a valid Bot API key. You can get this by navigating to Connect -> Api Keys for your bot and creating one with the Read chats scope.
Check out a full implementation example (in Python) here.