MS Title Group:
This device client access license (CAL) authorizes one computer to access SQL Server when the server is deployed using the Client/Server model. Any number of users can use the device (for example, a shared workstation).
User CALs are also available. A user CAL authorizes a user to access SQL Server from any device, For example, an employee might access the server from a computer at work and another at home.
This license does not require media, license keys, or setup codes.
Under the Software Assurance program, you have the right to install any new release of products covered in the agreement during the term of your coverage.
Product restrictions can be found under Microsoft's eligibility guidelines.