OEM, Retail or Volume: Which Windows Licence Type Actually Fits You?

Fix it now

The three channels wrap different contract terms around identical software. The decision is whether the licence has to outlive this hardware, and whether you need one activation mechanism for an estate. The trap to avoid is the big one: Microsoft states that Windows client volume licences cover upgrades only, and each machine still needs a qualifying retail or OEM licence underneath.

1. Do nothing if the PC came with Windows installed. You already hold an OEM licence, and reinstalling the same edition on that machine needs no second purchase.
2. Buy Retail when the licence has to outlive the hardware – a self-built machine, a box you expect to rebuild, or an entitlement you want to carry to a replacement PC.
3. Buy Volume when one imaging process and one activation mechanism are worth more than the per-licence difference, not because you think it is cheaper per seat.
4. Budget for the base licence before ordering volume Windows. Microsoft states that volume programme licences cover upgrades to Windows client operating systems only, and that an existing retail or OEM licence is needed for each computer first.
5. Check the activation mechanism against your size. Microsoft requires at least 25 client computers to activate Windows clients by KMS, and at least 5 for Windows Server; below that, MAK acts like a retail key that activates multiple computers.
6. Remember the reassignment rule before planning any move. Under Microsoft’s Product Terms a licence may not be reassigned less than 90 days since its last reassignment, except on permanent hardware failure or loss, or termination of the user’s employment or contract.

Editions differ by channel too. Microsoft’s distribution table lists Windows 11 Home and Pro through retail and OEM, and Windows 11 Pro, Enterprise and Enterprise LTSC through Commercial Licensing – so Enterprise is not something you can buy one of in a box.

If you already hold an OEM licence and are not rebuilding, stop here and buy nothing. Below is what each channel is actually for, the volume detail that catches first-time buyers, and how to tell what you are running.

Why it happens

OEM, Retail and Volume are not three qualities of Windows. They are three sets of contract terms wrapped around the same software: the installer, the features and the updates are identical. What differs is whether the licence can move to another machine, how it activates, and whether it stands on its own or sits on top of an entitlement you already hold. Choosing wrongly does not stop Windows working today; it stops it working the day you replace the hardware.

An OEM licence arrives preinstalled and is tied to the device. On any machine built in the last decade the key is written into firmware rather than printed on a sticker, which is why a clean install of the same edition activates itself without anybody typing anything. That convenience is the same mechanism that anchors the licence: the machine identifies itself, and no other machine can make that claim. A Retail licence is bought separately and is the channel to use when the entitlement needs to survive a rebuild. A Volume licence is bought under an agreement, activated against your own infrastructure rather than Microsoft’s servers, and exists to make managing a fleet practical.

The detail that catches first-time volume buyers is published plainly by Microsoft and is worth quoting to anyone building a budget: the licences provided through volume licensing programmes cover upgrades to Windows client operating systems only, and before those upgrade rights can be exercised, an existing retail or OEM operating system licence is needed for each computer. Buying a hundred volume Windows licences does not license a hundred bare machines. It licenses a hundred machines that already carry a qualifying Windows licence.

Editions are the other channel-dependent thing. Microsoft’s own distribution table lists Windows 11 Home and Windows 11 Pro as available through both Full Packaged Product and preinstalled on device, and Windows 11 Pro, Windows 11 Enterprise and Windows 11 Enterprise LTSC through Commercial Licensing. Enterprise is not something you buy one of in a box, which is a common source of confusion when somebody has read about a feature and gone looking for the licence.

Full reference

The three channels side by side

The volume detail that costs money

It is worth restating on its own because it is the single most expensive misunderstanding in this area. Microsoft’s guidance for planning volume activation says that the licences provided through volume licensing programmes cover upgrades to Windows client operating systems only, and that before the upgrade rights obtained through volume licensing can be exercised, an existing retail or OEM operating system licence is needed for each computer running currently supported versions of Windows.

In the normal course of events this is invisible, because business PCs are bought with Windows Pro preinstalled and the volume licence simply lifts them to Enterprise. It becomes expensive exactly once: when somebody buys machines without an operating system and expects volume keys to cover them. Ask the question before the hardware order, not after.

This is a Windows client rule. Do not extrapolate it to Windows Server or to Office, and if the answer matters to a purchase, get it confirmed in writing against the current Product Terms rather than inferred from this page.

Choosing the activation mechanism

• KMS: activations complete on your local network without individual computers connecting to Microsoft. Microsoft states the organisation must have at least 25 computers to activate Windows clients, and at least 5 to activate Windows Server.
• MAK: commonly used by organisations that have a volume agreement but do not meet the KMS threshold. Microsoft describes it as acting like a retail key, except that it is valid for activating multiple computers.
• Active Directory-based activation: similar to KMS, but the activated computer does not need to maintain periodic connectivity, because a domain-joined machine queries AD DS for a volume activation object stored in the domain.

Working out what a machine is running now

Microsoft documents two commands for this. slmgr /dli displays licence information for the installed active Windows edition, and slmgr /dlv displays detailed licence information; neither requires elevated privileges, and both accept an activation ID or All if you want to see every installed product. Microsoft does not enumerate the individual output fields, so read the description and channel information the output presents rather than expecting a specific field name to be documented.

slmgr /dli
slmgr /dlv
slmgr /dlv All

Which channel to buy, by situation

• You bought a laptop or prebuilt desktop with Windows on it: you are already licensed. Reinstalling the same edition from Microsoft’s own media reactivates against the firmware entitlement with nothing to buy.
• You are building one PC from parts and intend to keep upgrading it: Retail, because the entitlement survives rebuilds you have not yet thought of.
• You are deploying from a standard image across dozens of machines: Volume, for the deployment model and the single activation mechanism rather than for the licence itself.
• You need an edition only sold through Commercial Licensing, such as Enterprise or Enterprise LTSC: Volume is the only channel that carries it.
• You have fewer than 25 client machines but a volume agreement: MAK rather than KMS, because you are below the documented KMS threshold.

Two things to settle before you order

1. Support: who you call when activation fails differs by channel and by agreement. Settle it before the purchase rather than at the point of failure, and get the route in writing on the quote.
2. Reassignment: if the plan involves moving licences between machines, read the Product Terms rule first. Not less than 90 days since the last reassignment of that same licence, with exceptions for permanent hardware failure or loss and for termination of a user’s employment or contract – and the software must be removed or access blocked on the machine you moved away from.

Questions people ask about this