Free-tier accounts must use a bot at least once every 60 days. If no bots are used during this period, the account will be scheduled for deletion.
An email notification will be sent 60 days before the scheduled deletion date, followed by another reminder 7 days before deletion.
To prevent your account from being deleted, simply log in and use one of your bots. This will keep your account active and restart the 60-day inactivity period.