Erase all photos ever sent
It would be important from a security perspective that any user has the option to have all the content erased from all conversations (especially pictures). That way privacy can be maintained for discreet people and if you decide to log out for a while then no one has access to the photos you sent while you're away from the app.
Yes, like a snapchat and no screenshot .
Vengeful Toaster commented
expiring photo exists.