Google's Allo does not have a built in feature that lets users save copies of chats for later viewing, but an APK teardown of the latest version of the app shows that the feature may be coming in a future update. The code that was found seems to indicate that once the function rolls out, chat backups can not only be saved to external storage as the user pleases, they can be uploaded to Google Drive straight from Allo. Chats can also be restored from a backup in case a user reinstalls the app, gets a new device, or otherwise loses their Allo data.
It's unclear whether the chat backups can be read and modified outside of Allo, or if they'll be in some sort of encrypted or proprietary format for security. In any case, the backups will include things like pictures, emoji, and other bits and bobs that accompany text, even sent files. Users can do backups manually, or set the app to back up chats automatically at set intervals. Users can also choose what is backed up, whether that's just text, text and pictures, or the full package. When Allo detects recent backups of chats that it's either lacking or isn't up to date on, it will do the backup in the background and allow the user to continue using the app, including chatting to people involved in chats that are being restored.
The teardown revealed a number of other features. There were some tweaks to the upcoming quick selfie feature, including changes to the handling of the camera preview. Group incognito chats, a feature that popped up in earlier APK files, now has a new string of code referencing it. Finally, the feature allowing users to make sticker packs from their own selfies is back in force after being removed in earlier updates. The Allo 9.0 update is live in the Play Store right now, and none of these features are accessible to the user. Presumably, some or even all of them are nearing completion at this point and could even be turned on server-side without an update, should Google choose to approach them that way.