Microsoft licensing explained
Licensing models, end-of-support dates, CAL logic and buying with legal certainty. Explained plainly for purchasing and IT, without sales noise.
Where licensing usually goes wrong
Almost every expensive mistake in software procurement comes back to four causes. None of them is exotic, and none of them shows up until somebody does the math.
The client access licenses get forgotten
A server license permits the server to run, not access to it. Every user or device that reaches the server needs a client access license in addition. This item is regularly missing from calculations, and it is rarely a small one.
Support ends sooner than expected
A cheap older version is no advantage if the security updates run out in a year. Anyone who does not relate the price to the remaining lifespan is comparing two things that are not comparable.
License types get confused
Perpetual license, subscription, pre-installed license: from the outside the software looks the same, in law they are three different things. Only one of them becomes your property and may be passed on later.
The evidence is missing when it is needed
In a license audit what counts is not what is installed but what can be evidenced. An invoice on its own evidences your purchase, not the seller's entitlement. That difference tends to be noticed only when the question is asked.
What these pages are for
Licensing is needlessly complicated, and many bad purchases arise from misunderstandings: one CAL too few, the wrong licensing model for SQL Server, a version close to its end of support. These articles are meant to prevent mistakes like that.
If your question is not answered here, put it to us directly. Advice is part of what we offer and is not charged separately.
Terms that keep coming up
Twelve terms are enough to make sense of most licensing paperwork. Here they are in plain language.
Volume license
A license from a collective agreement covering several workstations or servers. It is tied to the company rather than to a device, and is therefore transferable in principle.
Perpetual license
Paid once, usable permanently. The counterpart to a subscription. Only a perpetual license becomes your property and can be resold later.
Subscription
A right of use for a period against recurring payment. When the payments end, the right ends. A subscription cannot be resold as a used license.
Exhaustion principle
The legal principle that the manufacturer cannot prohibit resale once it has sold the license outright. The basis of the entire used market.
Chain of title
The documented path of a license from the first purchase, across every previous owner, through to you. It is the evidence that the license was allowed to be transferred at all.
Decommissioning
The complete removal of the software at the previous owner, confirmed in writing. Without that declaration a transfer is not effective, because a license may be used only once.
Client access license (CAL)
Permission for a user or device to reach a licensed server. It comes on top of the server license and is frequently overlooked.
User or device
Client access licenses come in two forms. Where people use several devices each, licensing per user pays off; for shift work at fixed machines, licensing per device tends to.
Core-based licensing
With newer server versions the requirement follows the number of processor cores, usually with a set minimum per server. The hardware therefore has a say in what has to be licensed.
Downgrade right
Permission to run an older version instead of the one licensed. Useful where a business application requires a particular version but the license is newer.
End of support
The point from which the manufacturer no longer supplies security updates. The software remains usable afterwards, but it becomes a growing risk and is often a topic in audits.
License audit
The check on whether the software in use is covered by licenses. What is examined is your evidence, not your intentions. The documentation decides, not anyone's recollection.
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