Windows Server 2025 - 1 User CAL is the cloud-ready operating system that supports your current workloads while introducing new technologies that make it easy to transition to cloud computing when you're ready.  A Client Access License (CAL) is required for each user or device that accesses Windows Server or Windows Datacenter server software. This license is for one user who accesses the server.
 
A User Client Access License (CAL) is essential for several reasons when accessing Windows Server environments:
Access Control:
A User CAL allows a specific user to access the server from any device. This is particularly useful in environments where users need to access the server from multiple devices, such as desktops, laptops, and mobile devices.
Cost Efficiency:
In scenarios where users access the server from multiple devices, a User CAL can be more cost-effective than purchasing individual Device CALs for each device. This helps optimize licensing costs while ensuring compliance.
Compliance and Legal Requirements:
Microsoft’s licensing terms mandate that every user or device accessing the server must have a corresponding CAL. This ensures that organizations remain compliant with licensing agreements, avoiding potential legal and financial penalties.
Flexibility in Licensing:
User CALs provide flexibility in environments with a high user-to-device ratio. They are ideal for situations where users need to access the server from various devices, ensuring that each user is properly licensed regardless of the number of devices they use.
Simplified Management:
Managing User CALs can be simpler in certain environments, as it involves tracking the number of users rather than individual devices. This can streamline the administrative process and reduce the complexity of license management.
 
By ensuring that each user accessing the server is properly licensed, User CALs help maintain compliance, optimize costs, and provide flexibility in various organizational setups.