Explanation
Oracle Cloud Infrastructure automatically backs up your Autonomous Databases and retains these backups for
60 days. Automatic backups are weekly full backups and daily incremental backups. You can also create manual backups to supplement your automatic backups. Manual backups are stored in an Object Storage bucket that you create, and are retained for 60 days The retention period for manual backups is the same as automatic backups which is 60 days. So we cannot preserve the backup for 12 months
https://docs.oracle.com/en/cloud/paas/autonomous-data-warehouse-cloud/user/backup-manual.html#GUID-D95E