[mike-cardwell]

"there is no way to detect someone uninstalling without unregistering"

The TextSecure app could ping your server with a "I am still here" message if it goes a week without sending any messages. Don't hear from it for two weeks? Unregister it.

Would this not work?

[waxjar]

Not having a connection for a month doesn't necessarily mean you're not "still here".

[ianopolous]

But it does mean messages can't be delivered to you.