Customers that have enrolled in WS2012/ R2 ESUs through Volume Licensing for Year 1 can transition to Azure Arc for Year 2 of the program. Extended Security Updates afford customers with critical security patches for end of support Windows Server 2012/R2 machines. ESUs are available at no additional cost to customers running on Azure VMs or Azure Stack HCI. For customers running on-premises or other public clouds, WS2012/R2 ESUs are a paid offer.

The WS2012/R2 ESUs enabled by Azure Arc affords key advantages compared to ESUs through Volume Licensing including:

Pay as you Go flexibility to scale down WS2012 ESU consumption consumptively as customers migrate workloads to Azure and modernize affording flexibility. 
Ability to apply Azure Discounting with the decrement of a Microsoft Azure Consumption Commitment (MACC) affording significant financial benefits. 
Azure management capabilities including Azure Update Manager, Azure Change Tracking and Inventory, and Azure Machine Configuration are available at no additional cost.

For enrollment, customers must specify their Year 1 Volume Licensing entitlement, indicating their Invoice Id (Invoice Number) to reflect their MAK Key entitlement at the time of Azure Arc WS2012 / R2 ESU license provisioning. This is available directly in the Azure portal with the current experience for Create an Extended Security Updates license. Programmatically, customers can use Azure CLI to generate new licenses, specifying the new Volume License Details parameter in az connectedmachine license | Microsoft Learn their Year 1 Volume Licensing entitlements by entering their respective Invoice Numbers. Customers must explicitly specify the Invoice Id (Number) in their license provisioning for Azure Arc.

Customers that make this indication in their license creation will not be back billed for Year 1 of Extended Security Updates, with billing to commence from the start of Year 2 of Windows Server 2012/R2 Extended Security Updates. Customers do not need to deactivate existing MAK Keys or unenroll from ESUs through Volume Licensing to enroll in WS2012/R2 ESUs enabled by Azure Arc. See enrollment steps at Deliver Extended Security Updates for Windows Server 2012 – Azure Arc | Microsoft Learn. After reviewing Azure Arc and licensing terms, connect your servers to Azure Arc, provision new WS2012/R2 ESU licenses in Azure portal specifying Volume Licensing entitlements, and link your servers to these licenses for enrollment. With just three months until the end of Year 1, the time is now to transition to WS2012/R2 Extended Security Updates enabled by Azure Arc. 

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