Final answer:
Visual Studio Team Foundation Server 2018 is licensed per user with Standard and Enterprise client access licenses (CALs), and may require a server license and a Microsoft SQL Server license. A TFS Device CAL is available, and TFS Express Edition is free for up to five users. Larger teams might benefit from a Visual Studio Subscription, which includes TFS CALs.
Step-by-step explanation:
Visual Studio Team Foundation Server 2018, also known as TFS 2018, is licensed on a per-user basis. Each user that accesses the TFS server requires a client access license (CAL), which comes in two forms: Standard and Enterprise. A Standard CAL enables a user to access most TFS features, while an Enterprise CAL provides additional features such as test case management and web-based test execution.
For teams that include non-developers who only need to work with work items or track project progress, a TFS Device CAL might be more cost-effective. Such a CAL allows multiple non-developers to use a single device to access TFS. Servers hosting TFS also need to be licensed, which typically involves purchasing a TFS server license separately. Furthermore, TFS can be integrated with Microsoft SQL Server, which requires its own license.
There are special licensing options for Volume Licensing customers and for smaller teams, like the TFS Express Edition, which is free for up to five users. Microsoft also provides a Visual Studio Subscription, formerly known as MSDN subscription, that includes a TFS CAL and additional benefits like access to Azure DevOps, among other resources.