RDS CAL Explained: Per User vs Per Device (Windows Server)

You set up Remote Desktop on your Windows Server, staff start logging in, and around day 120 everyone gets: "The remote session was disconnected because there are no Remote Desktop License Servers available." That's the grace period ending. You need RDS CALs. Here's everything in one place.

What is an RDS CAL?

A Remote Desktop Services Client Access Licence allows one user or one device to use Remote Desktop Services (the multi-user remote desktop/RemoteApp feature) on Windows Server. Without them, Windows Server only allows two admin sessions for management.

Note: RDS CALs are in addition to the normal Windows Server CALs.

Per User or Per Device?

• Per User: one CAL per person, no matter how many devices they use. Best when staff connect from a laptop, home PC and phone.
• Per Device: one CAL per computer, no matter how many people use it. Best for shared PCs — billing counters, factory terminals, shift workers.

Example: a CA firm with 12 staff who work from office and home → 12 Per User CALs. A shop with 5 billing PCs used by 15 people in shifts → 5 Per Device CALs.

The version rule

RDS CALs must be the same version or newer than the server they connect to. A 2022 RDS CAL works on Server 2022, 2019 and 2016 — but not on Server 2025. So buy CALs matching your newest server.

How to install RDS CALs (quick steps)

1. Install the Remote Desktop Licensing role (Server Manager → Add Roles and Features).
2. Open RD Licensing Manager, right-click your server → Activate Server.
3. Right-click again → Install Licenses → choose the licence programme and enter your licence details.
4. In RD Session Host configuration, set the licensing mode (Per User or Per Device) and point it to your licence server.
5. Run RD Licensing Diagnoser — no errors means you're done.

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