Addressed EEE doc ask #26863442

Author: AbhishekMallick01

articles/backup/encryption-at-rest-with-cmk.md

@@ -2,7 +2,7 @@
 title: Encrypt backup data by using customer-managed keys
 description: Learn how to use Azure Backup to encrypt your backup data by using customer-managed keys (CMKs).
 ms.topic: how-to
-ms.date: 07/30/2024
+ms.date: 05/26/2025
 ms.custom: devx-track-azurepowershell-azurecli, devx-track-azurecli
 ms.service: azure-backup
 author: jyothisuri
@@ -586,6 +586,10 @@ If you don't follow the steps in the article and you proceed to protect items, t
 
 Using CMK encryption for Backup doesn't incur any additional costs. But you might continue to incur costs for using your key vault where your key is stored.
 
+### What happens to data encrypted with a CMK after its expiration?
+
+When a Customer Managed Key (CMK) expires, it can still unwrap keys, allowing backup and restore operations to succeed. However, it cannot encrypt new vaults. To ensure continuity, enable key rotation to automatically generate a new version upon expiration. Learn about [Key types, algorithms, and operations](/azure/key-vault/keys/about-keys-details).
+
 ## Next steps
 
 [Overview of security features in Azure Backup](security-overview.md)