Update manage-asset-concept.md

Author: Juliako

articles/media-services/latest/manage-asset-concept.md

@@ -54,6 +54,8 @@ After the digital files are uploaded into storage and associated with an Asset,
     ```
 2. Get a SAS URL with read-write permissions that will be used to upload digital files into the Asset container. You can use the Media Services API to [list the asset container URLs](https://docs.microsoft.com/rest/api/media/assets/listcontainersas).
 
+    If using Asset’s ListContainerSas function to get SAS URLs, note that the function returns multiple SAS URLs as there are two storage account keys for each storage account. A storage account has two keys because it allows for seamless rotation  of storage account keys (for example, change one while using the other then start using the new key and rotate the other key). The 1st SAS URL represents storage key1 and second one storage key2.
+    
     **AssetContainerSas.listContainerSas** takes a [ListContainerSasInput](https://docs.microsoft.com/rest/api/media/assets/listcontainersas#listcontainersasinput) parameter on which you set `expiryTime`. The time should be set to  < 24 hours.
     
 3. Use the Azure Storage APIs or SDKs (for example, the [Storage REST API](../../storage/common/storage-rest-api-auth.md) or [.NET SDK](../../storage/blobs/storage-quickstart-blobs-dotnet.md)) to upload files into the Asset container.