How annoying it is when your friends delete their messages before you can see them?
The curiosity takes over. You just found the solution: WAMR!

WAMR is the utility you were looking for. With one tool you are able to recover text messages and also any media attachment (pictures, videos, voice notes, audio, animated gifs and stickers)!
All with one app!

HOW IT WORKS
Messages are encrypted on your device so WAMR can't access them directly.
The only solution available is to read them from the notifications that you receive and create a message backup based on your notification history.
When WAMR will detect that a message as been deleted, it will immediately show you a notification!

MEDIA MESSAGES
WAMR will also try to save any media attached to the message and if the sender deletes it, you will receive a notification.
The following media types can be recovered: pictures, videos, animated gifs, audio, voice notes, documents, stickers.

<font color="red">LIMITATIONS</font>
Please be aware that it doesn't exist an official and supported way to recover deleted messages. This is a workaround and may encounter limitations caused by the selected messaging app or even the Android OS:
1) Text messages are recovered by your notifications, therefore, if you have put a chat on silence, or if you are currently watching a message on the messaging app before it's deleted you will not receive a notification so WAMR can't save it! This also obviously means that is impossible to recover notifications/messages before you downloaded this app (so download it quickly!).

2) If messages aren't being saved, it may be caused by Android stopping WAMR. Please remove WAMR from all battery optimization services!

3) WAMR can't save files if they aren't completely downloaded! So if you are offline or you have an unstable connection, or in general if the sender deletes the message containing a media before the messaging app downloads it, WAMR can't do anything to save it.

4) If you aren't using a WiFi connection, some media may not be automatically downloaded by your messaging app because of your settings. You can change this behavior in Messaging app > Settings > Data and storage usage and increase your chances.

Other limitations may be caused by your Android version, or your system language (in particular if it is right-to-left). Please feel free to contact me and submit me any problem so I can try to fix it!

WAMR never collects your private messages or similar. Everything is saved only on your phone, locally.