Customers who have Windows Server licences with active Software Assurance can take advantage of the Azure Hybrid Benefit which allows them to assign these licences to Azure. This means that they can run Windows Server virtual machines at a reduced cost, paying just the base compute charges in Azure. It’s possible to deploy a new VM using the Azure Hybrid Benefit or to update an existing running VM to use this benefit. This is a useful article if you want to see how this is done and to get a view of which deployed VMs are using the Azure Hybrid Benefit: http://bit.ly/2tgbUdC.