Retention Policy and Incremental Backups
Incremental backups only have the data that's changed from one run to the next. Different data may change each time, meaning that each Incremental may have different data than the others. Therefore, Incremental backups form a "chain", and all of them are required in order to have a complete record of all data for restore.
Because of this, CloudBackupNow! has an override for retention policy known as "Keep Backup If Dependent Backup Exists", and it is on by default.
If this override is checked, a backup will not be purged if another backup depends on it. This option ensures that you have all the data that is needed to perform a complete restore to any available backup point.
The entire "chain" of backups will be purged when the most recent backup in the chain reaches its retention. So, for example, if you run a new Full Backup and start a new chain of Incrementals, the old chain will be purged five days later when the last Incremental expires.
There is a similar override to prevent the most recent Full Backup from being purged.
Both overrides are enabled by default for customer protection. They can be disabled from the Retention menu.