An account is inactive if its owner hasn't logged into the dashboard, CLI, or API within the last 365 days, and no paid resources were used with Heroku within the last six months. To keep your account active, you must log back into your account via the dashboard or the CLI by October 26, 2022.
In addition to our plans for inactive account deletion, Heroku is also ending free Heroku Dynos, free Heroku Postgres and free Heroku Key-Value Store plans starting November 28, 2022. You must upgrade your free dynos and data add-ons to paid plans before this date to avoid disruption to your apps or the deletion of data. See our Removal of Heroku Free Product Plans FAQ for more info.
See our blog post and the Removal of Heroku Free Product Plans FAQ for more info related to the ending of free plans and inactive account deletion.