Heroku Changelog Automatic app archiving

Change effective on 26 August 2013

Heroku will now automatically archive apps older than 3 months that have never had a user-initiated deploy. That means only empty apps, or apps created from templates and never changed, will be archived. An archived app will not be running any dynos and will yield a “No such app” response when accessed using its .herokuapp.com domain.

Read more about app archiving on Dev Center.