Device vs. User Client Access License
With most products, you must acquire a license for each running instance of the server software you run on a server. There are two types of CALs: Device CALs and User CALs.
Device CAL – Licenses a device for use by any user.
User CAL – Licenses one user to use any device.
Note: CALs are version specific. You must have CALs for the same version or later that the server software being accessed. To cut down on the number of users or devices that access software on a server, some organizations implement network architectures, called multiplexing or pooling.