WhatsApp has had a disappearing messages system for a couple of years now, letting you set certain chats to wipe their messages after seven days if you're concerned about privacy or just want to avoid an ever-expanding archive.

Now, though, it might be working on a mechanism to let you mark certain messages in those chats for retention, allowing you to keep messages that might have useful information you need going forward, for example.

This comes courtesy of WABetaInfo, which has spotted the addition of a new "Kept Messages" option under chat settings in the latest beta version of WhatsApp, which it has taken apart.

That reveals the sub-menu, which suggests that you'll be able to mark certain messages to be kept, although we don't know if there will be a limit on how many you can retain.

It would also be interesting to learn how this might work in group chats, where you might presumably need others' permissions to mark messages for keeping.

Still, the idea of the setting confirms that WhatsApp is probably looking at helping people keep hold of messages they're liable to want in more than a week's time. There's no timeline on when we might expect it to hit the actual app, though, as yet.