Retail, OEM, Volume, MAK, KMS — the words that appear in software listings mean real, specific things, and the differences decide whether you can move your licence, how long it lasts and who you can legally sell it to. Here is what each one is, in plain English.
Why this matters before you buy
Two listings can both say “Windows 11 Pro” and both be genuine, and still be worth very different amounts of money. The difference is the licence type. It is not a technical detail for IT people — it determines what happens the day your motherboard dies or you buy a new laptop.
A seller who will not tell you the licence type is not necessarily selling you something fake. But they are selling you something you cannot evaluate.
Retail
A retail licence is the one Microsoft sells to an individual in a shop or online.
- Transferable. You can remove it from one computer and activate it on another. This is the defining feature.
- Tied to you, not to a machine. It can follow you through several computers over the years.
- Eligible for Microsoft support directly.
- The most expensive kind, for exactly these reasons.
If you expect to change or rebuild your PC, retail is what you want.
OEM
OEM stands for Original Equipment Manufacturer. These are the licences that come pre-installed on a new computer from Dell, HP, Lenovo and so on.
- Permanently tied to the first machine it activates on. Once bound, it stays bound.
- Not transferable. If that computer dies, the licence dies with it. Replacing a motherboard usually counts as a new computer.
- Support is the responsibility of the hardware maker, not Microsoft.
- Considerably cheaper than retail.
OEM is perfectly legitimate and perfectly sensible — for a machine you will keep until it stops working. It is the wrong choice if you build or upgrade your own PCs.
Volume licensing (MAK and KMS)
Volume licences are what Microsoft sells to organisations buying in bulk — companies, schools, government bodies. They come in two activation flavours.
MAK (Multiple Activation Key) is a single key with a set number of activations. An organisation with 200 PCs gets one key good for 200 machines, and each activates against Microsoft once.
KMS (Key Management Service) works differently: machines activate against a server inside the organisation’s own network and re-check roughly every 180 days. Take that machine off that network permanently and activation eventually lapses.
This is the part worth understanding as a buyer. A KMS-activated key sold to a home user is a licence that expects a corporate server it will never see again. It may activate today and stop later. A MAK key from a volume agreement is more durable, but the agreement it came from was never written to cover resale to individuals.
The practical test: ask the seller whether the key is retail, OEM, MAK or KMS, and whether it can be moved to another computer. A straight answer tells you what you are buying. No answer tells you something too.
Where the very cheap keys come from
If a Windows or Office key costs a small fraction of the retail price, the money has to come from somewhere. The usual explanations are:
- Volume keys split up and resold individually — cheap because one organisational key is being sold many times over.
- Keys bought in a country with much lower pricing and resold elsewhere, outside the territory they were licensed for.
- OEM keys sold detached from hardware, which is not how they were meant to be distributed.
Some of these keys work for years. Some stop working at the first major update or the first time Microsoft audits a key block. The risk is not that the software is a virus — it is that you have no recourse when activation fails, because the seller has usually gone.
What a straight answer looks like
Before you pay, you should be able to find out:
- The exact edition and version.
- The licence type — retail, OEM or volume.
- Whether it can be transferred to another computer.
- What happens if it fails to activate, and how long you have to claim.
- Who the seller legally is — a registered company with an address, not just a storefront.
Those five answers are the whole of due diligence. Any honest seller can give them in a sentence each.
We state the licence type on every product page, we are a UK registered company with a published address and company number, and every key carries a 30-day guarantee: if it will not activate and we cannot fix it, you get a replacement or your money back.
A note on “lifetime”
“Lifetime” is a marketing word, not a licensing term. For a perpetual Windows or Office licence it usually means for the supported life of that version on that device — which is a real and useful thing, but it is not the same as forever on any machine. When a listing says lifetime, the question to ask is the same as always: retail or OEM, and can it move?