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Licensing Microsoft Windows Server in SPLA

Windows Server SPLA licensing. Let's try and explain it in simple terms.

When you rent Microsoft Windows Server virtual machines from a service provider, they require licenses. There are always two perspectives on SPLA licensing: the provider's perspective and the end customer's. We'll cover both in this quick reference guide.

Note: please come to this page after October 01, 2022. Windows Server SPLA licensing terms will significantly change on that day.

Frequently asked questions

May end customers bring their own Windows Server licences (BYOL) to a provider?

Dedicated hardware

Multi-tenant hardware

Yes, volume licences with or without Software Assurance and CSP licences except on "Listed Providers" (see notes below the table).

No, it's currently not allowed. However, it shall be permitted after October 01, 2022, via the Flexible Virtualization benefit.

Dedicated hardware on "Listed Providers" – Amazon, Google, Azure, Alibaba – differs from all other providers ("Authorised Outsourcers"). You may only BYOL licenses bought before October 2019.

Are Windows Server Client Access Licences (CALs) required in SPLA?

When you license Windows Server via SPLA, Windows Server CALs are not required. However, other types of Client Access Licences are required if you use any additionally licensed functionality of Microsoft Windows Server. Such licences in SPLA are called "Subscriber Access Licences" or SALs:

  • Windows Server Active Directory Rights Management SAL,

  • Windows Server Remote Desktop Services SAL,

  • Microsoft Identity Manager SAL.

Note that SALs are typically licensed per user but may also be per device.

May I bring my own RDS CALs to a provider?

Yes, that is allowed for RDS User CALs similar to Azure. You must first complete the License Verification Form and send it to Microsoft.

What Windows Server versions can I run in SPLA?

Any version. SPLA licences are always of the most current version. SPLA also includes downgrade rights.

Running out-of-support versions is compliant but ask your provider if they are willing to take security risks.

What Windows Server editions are available through SPLA?

SPLA licences are available in the following editions:



Windows Server Datacenter


Windows Server Standard


Windows Server Essentials


What license do I need for Windows Server Enterprise in SPLA?

To run a Windows Server Enterprise instance in SPLA, you must license it as Windows Server Standard.

That is because the Windows Server Enterprise edition was deprecated in 2012. The last released version was Windows Server Enterprise 2008 R2.

May I use Windows Server Datacenter licenses on a multi-tenant host?

If you assign SPLA Windows Server Datacenter licenses to a host, you are permitted to run virtual machines from multiple end clients. In this case, the answer is yes.

However, licenses acquired in the Volume Licensing channel or via CSP are only permitted on a single-tenant host. This will change on 01 October 2022 – please come back to this article after that date.

Microsoft Windows Server licensing for providers

Calculating Windows Server Datacenter and Standard core licenses

The quantity of required Windows Server Datacenter or Standard SPLA licenses depends on the number of physical cores on the host (subject to change on October 01, 2022).

  1. Count physical cores in each processor. Hyper-threading does not matter.

  2. Assign the number of single-core licences equal to the number of cores in a processor but not less than eight.

Here's a formula for Microsoft Excel:

=MAX(8, CoresPerProcessor) * Processors

Pay attention that the price list item is a two-core pack. Therefore, to calculate the number of core packs to report to your SPLA reseller, use this formula:

=MAX(8, CoresPerProcessor) * Processors / 2

Windows Server Datacenter and Standard in VMware, Hyper-V, and KVM

Regardless of the host's hypervisor, here are the basic rules:

  • For an unlimited number of virtual machines, assign Windows Server Datacenter licenses to the host.

  • Windows Server Standard licenses assigned to the host only permit running one virtual machine. Please note that it's not two virtual machines like in volume licensing.

Let's look at some advanced scenarios.

If you have a standalone host – not a cluster member – with multiple Windows Server Standard virtual machines, use this formula to calculate Windows Server Standard core packs:

=MAX(8, CoresPerProcessor) * Processors * VMs / 2

Pro tip: After approximately seven Windows Server Standard virtual machines on the host, Windows Server Datacenter core licenses become cheaper. The breakeven point for Core Infrastructure Suite is approximately four virtual machines. Check your price list.

If you have a low number of Windows Server Standard-only virtual machines in a cluster, it may also be cheaper to license it with Windows Server Standard. However, due to Microsoft demanding the hosts to be licensed for the maximum number of virtual machines, you need to multiply all licensable cores in the cluster by the number of Windows Server Standard virtual machines:

=SumOfLicensableCoresInTheCluster * VMs / 2

where for each host, licensable cores are:

=MAX(8, CoresPerProcessor) * Processors

Pro tip: After approximately seven Windows Server Standard virtual machines in the cluster, Windows Server Datacenter core licenses become cheaper. The breakeven point for Core Infrastructure Suite is approximately four virtual machines. Check your price list.

How to calculate Core Infrastructure Suite licenses in SPLA

All the rules for Windows Server (Datacenter and Standard) also apply to Core Infrastructure Suite (CIS).

How to calculate RDS SALs in SPLA

An access license is required for each authorised user regardless of their activity.

  • Find out what security groups are authorised to access Remote Desktop (not Remote Desktop Administration),

  • Count all persons in all those groups and nested groups (don't include service accounts).

Activity or inactivity of users does not affect the number of required client licenses in SPLA. If a person has access, they need a license.

The provider may deduct two users accessing servers for the sole purpose of testing, maintenance, and administration of products from this number. They don't require SALs.

Bringing your Windows Server SPLA licenses to a different Data Centre Provider (DCP)

Windows Server core and processor licenses are not DCP eligible. The provider that owns the data centre must report Windows Server licenses through their SPLA.

All SALs are DCP eligible. A provider may report SALs through their own SPLA even if they deploy Windows Server workloads to a different Data Centre Provider.

Microsoft Windows Server licensing for SPLA clients

"Listed providers" are Amazon AWS, Google GCP, Microsoft Azure, and Alibaba. All the rest are "Authorised outsourcers".

Until October 01, 2022, you have the following options:


Dedicated hardware in "Listed providers"

Dedicated hardware in "Authorised outsourcers"

Multi-tenant, Public Cloud

Bring your own licences (BYOL)

Restricted (see notes below the table)






Dedicated hardware on Listed Providers differs from all other providers ("Authorised Outsourcers"). You may only deploy licenses bought before October 2019.

The licences you take (bring) to a provider to use on dedicated hardware are governed by Microsoft Product Terms. It means that all the rules are the same as on-premises.

Still confused? Talk to a SPLA expert

Our team of SPLA experts are here to help. Use the form below to get in touch today. We can assist with everything from licensing audits to subscription management in Microsoft SPLA.