The data archive mechanism with SQL Server in an Azure virtual machine generally will be a full SQL Server backup that you store for the length of time required. If you are managing your own backups, you will want to store your full database backups in Azure blob storage standard storage (or archive outside Azure). If you are not already using backup to URL to store your backups in Azure blob storage, you will want to copy from your attached disks in premium storage to Azure blob storage using standard storage.
If you are using managed backup and want to archive a full database backup for longer than 30 days, you will need to copy a full backup to a new storage location or periodically perform a full database backup (to URL) on a scheduled basis and store it in standard storage for the length of time required.
If you are using file-snapshot backup, you have another option to archive your database: you periodically can copy the backup snapshots for a given backup set to long-term storage. At any point in time, you can choose to restore to a new database when needed and create a traditional (streaming) SQL Server backup for long-term storage.
Source of Information : Migrating SQL Server Databases to Azure