Software Assurance (SA) is a simpler way of obtaining the latest and most innovative Microsoft products, replacing the complexity of one-time upgrades (VUP - Version Upgrade; PUP - Product Upgrade; CUP - Competitive Upgrade; LUP - Language Upgrade) and Upgrade Advantage (UA). With Software Assurance, you receive the right to run the current version of the product as well as any new versions released during the term of your coverage.
A Windows® Server Client Access License (CAL) is required for each user or device (or combination of both) that accesses or uses the server software. Licensing options let you choose the CALs that make economic sense for your network.
User-based Client Access Licenses
Windows User CALs might make the most sense if your organization has many roaming employees who need access to the corporate network from unknown devices or employees who access the network from multiple devices.