@MENGYING LI Thank you for reaching out to us!
I understand that you are looking for expiry time of on-demand backup over 15 days.
For Azure VMs, in the job details page (for on-demand backup jobs), users can see the expiry time for the recovery point based on the expiry time that they had set while creating the on-demand backup. Is this what you are looking for?
Update:
In Backup center we show jobs for the last 15 days because this view is meant more for operational monitoring. In Recovery Services vault, you can see jobs for a slightly longer duration of time.
For jobs older than 6 months, we recommend not to take dependency on these views and instead use Log Analytics to store older jobs information.
More details in the ‘Note’ under this section https://learn.microsoft.com/en-us/azure/backup/backup-azure-monitoring-built-in-monitor?tabs=recovery-services-vaults#backup-jobs-in-backup-center
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