Windows Server & SQL Server Licensing: Your Questions Answered

Microsoft server licensing works differently from Windows or Office. You license the physical cores in your server, the people or devices that connect to it, and Remote Desktop access if you use it. This page answers the questions business customers ask us most, so you can buy the right licences first time. If your setup isn't covered here, message us on live chat with your server's core count, number of VMs and number of users, and we'll put together a quote.

Licensing your server

How is Windows Server licensed?

Windows Server 2025, 2022 and 2019 Standard and Datacenter are licensed per physical core. Every physical core in the server must be licensed, with a minimum of 8 cores per processor and 16 cores per server, even if the server has fewer. Our Windows Server licences cover up to 16, 24 or 32 physical cores per server, depending on the product.

Standard or Datacenter: which do I need?

The difference is virtual machines.

  • Standard covers 2 virtual machines (plus the Hyper-V host itself) once all the server's physical cores are licensed. For 4 VMs, license the cores twice; for 6 VMs, three times.
  • Datacenter covers unlimited virtual machines on a fully licensed server.

For example, a 16-core server running 4 Hyper-V VMs needs 2 Standard licences covering 16 or more cores, or 1 Datacenter licence. If you plan to run more than 4 VMs, Datacenter is usually the simpler choice.

My VMs only have 4 or 8 virtual cores. Do I license those?

No. Windows Server is licensed by the physical cores in the host, not by the virtual cores you give each VM. A 24-core licence covers a physical server with up to 24 cores, however you divide them between VMs. The number of VMs you can run depends on your edition, as explained above.

My server has more cores than your licence covers (for example, 64 cores).

Core licences add up. A 64-core server needs licences covering all 64 physical cores, for example three 24-core licences (72 cores). You activate the server with one product key; Windows doesn't count cores during activation, so keep your invoices showing enough core licences for every server. For large core counts, message us for a quote.

What does "1 / 3 / 5 Devices" mean? Do I get one key or several?

You get one product key that activates on that number of servers. "5 Devices" means one key for up to 5 servers. Each server must still meet the core rules above. If you buy the same product again (for example, 2 × "5 Devices"), we upgrade your existing key to cover the extra servers instead of sending a new one.

Client Access Licences (CALs) and Remote Desktop

What is a CAL, and do I need one?

Every user or device that connects to Windows Server, whether for file sharing, printing, Active Directory or apps such as an ERP, needs a Windows Server CAL. CALs come in two types:

  • User CALs are best when each person uses several devices (laptop, phone, home PC).
  • Device CALs are best when several people share one device, such as shift workers, a classroom or a reception PC.

What are RDS CALs, and do I need them as well as Windows Server CALs?

Yes, you need both. Anyone who connects through Remote Desktop Services needs a Windows Server CAL and a Remote Desktop Services (RDS) CAL. RDS CALs come as User or Device CALs, just like Windows Server CALs.

One exception: up to 2 administrators can connect by Remote Desktop to manage the server without RDS CALs.

Do RDS User CALs work on Windows Server 2025 Datacenter?

Yes. RDS CALs work with both Standard and Datacenter. What matters is the version: your CALs must be the same version as the server or newer. Windows Server 2025 CALs work on Server 2025, 2022 and 2019. Server 2019 CALs don't work on a Server 2022 or 2025 machine.

User or Device RDS CALs: which should I buy?

Count whichever is smaller. If 60 students share 60 thin clients across the day, 60 Device CALs cover everyone. If 15 staff each use a laptop and a home PC, 15 User CALs are cheaper than 30 Device CALs.

Do I need an agreement number to activate RDS CALs?

No. Agreement numbers only apply to Microsoft volume licensing contracts. Our RDS CALs are retail licence packs, so you just need the key we send you.

How do I activate RDS CALs?

On the server running the Remote Desktop Licensing role:

  1. Open Remote Desktop Licensing Manager, right-click your server and choose Activate Server (if it isn't activated yet).
  2. Right-click again and choose Install Licenses.
  3. For the licence program, select License Pack (Retail Purchase) and enter the key we sent you.
  4. In your Remote Desktop Session Host settings, set the licensing mode (Per User or Per Device) to match the CALs you bought.

Until the CALs are installed, Remote Desktop works for a 120-day grace period.

SQL Server

How is SQL Server 2025 Standard licensed?

Our SQL Server 2025 Standard is a retail key that licenses SQL Server for one user. Buy one licence for each person who will use the database. For example, a team of 15 needs 15 licences. For large or growing teams, message us: licensing by core may work out cheaper, and we'll quote both options.

Office on a Remote Desktop server

Can I run Office for multiple users on a Remote Desktop server?

Yes, with Microsoft Office LTSC Professional Plus 2024. Microsoft supports Office LTSC 2024 on Windows Server 2022 and 2025. It isn't supported on Windows Server 2019; for a Server 2019 Remote Desktop server, use Office Professional Plus 2021 or upgrade the server.

Installation and delivery

How is it delivered? Is it a physical product?

Everything is delivered digitally by email. You'll receive your product key and installation instructions, usually within an hour of payment. You install from official Microsoft media.

Where do I download Windows Server?

From Microsoft's Evaluation Center. Install the evaluation edition, then convert it to the full edition with your key by running this in an administrator command prompt:

DISM /online /Set-Edition:ServerStandard /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /AcceptEula

For Datacenter, use ServerDatacenter. The server restarts, and Windows then activates with your key.

Can I use these licences on a cloud server?

These licences are for your own physical server, or a dedicated server you rent that isn't shared with other customers, plus the VMs running on it. They can't be used on shared cloud VMs from Microsoft Azure, AWS, Google Cloud or Alibaba Cloud. Those providers either include the Windows licence in their hourly price or require Microsoft Software Assurance to bring your own licence. If you rent a server, ask your host whether it's dedicated hardware and whether Windows is already included.

Buying for a business

What type of licence is this?

Our server licences are OEM or retail, depending on the product. OEM licences stay with the server they're first installed on and can't be moved to a new server. Retail licences can be moved to a replacement server. If this matters for your setup, ask us which type applies before you buy. Nerdused is a member of the Microsoft Partner Network (Partner ID 6467441).

Can I use the licences in any country, for commercial use?

Yes. Our keys have no regional restrictions and can be used commercially in any country.

Can I get an invoice in my company's name and tax ID?

Yes. Every order includes an invoice from Transfleet Trading Ltd (trading as Nerdused), a UK registered company. Send us your company name, address and tax ID (VAT, RFC, etc.) and we'll issue the invoice in your company's name.

What proof of licence do I get? What happens in a Microsoft audit?

Every order comes with:

  • your product keys
  • a full invoice from Transfleet Trading Ltd - Nerdused in your company's name and with your tax ID
  • your order record, showing the products, quantities and date of purchase

Keep these with your licensing records. If Microsoft or an auditor asks about your licences, contact us and we'll help you through the process. It's easier than you think. We'll give you copies of your purchase records and help you match your licences to your servers, users and devices.

What if my key stops working?

Every order is covered by our 30-day refund guarantee: if a key won't activate, we'll replace it or refund you. After the first 30 days, if you have any licensing issue, contact us and we'll arrange a replacement key or have our technical team help you resolve it.

I need a quote for multiple servers or a large number of users.

Message us on live chat or email hello@nerdused.com with the server core count, number of VMs, number of users or devices, and which editions you need. We'll reply with a quote the same day.