In my continued effort to help average people understand Microsoft licensing, I offer the following list of basic vocabulary you need to know when dealing with licensing. Although this is not the most exciting blog post you will ever read, it should prove useful as a point of reference.
License: a limited set of permissions granted by the manufacturer to the customer which governs how the software is deployed and used. See here for more information.
Perpetual License: a license that never expires; you have the manufacturer’s permission to use the software forever.
Subscription License: a license that eventually expires; you are allowed to use the software for a limited amount of time, but when that time period expires you either need to renew the subscription or uninstall the software.
Software Assurance (SA): a combination of services and additional use rights granted to the customer for a limited period of time.
Use Rights: a limited set of permissions granted by the manufacturer to the customer that dictate how the product can be used.
Server Licensing Terms
Server/CAL Model: a licensing model for certain server products which requires a license for the server and “client access licenses” (a.k.a., “CALs”) for each user or endpoint device that will access that server.
Per Processor Model: a licensing model for certain server products which requires a license for each processor in the server, but does not require a CAL for the users or endpoint devices.
Per Core Model: a licensing model for certain server products which requires a license for each processor core in the server, but does not require a CAL for the users or endpoint devices.
Multiplexing: a configuration of two or more servers where one system sits in front of another system providing services to endpoint devices. The endpoints communicate with the frontend server and then the frontend server communicates with the backend server, so the endpoints don’t communicate directly with the backend server. There are certain scenarios where a CAL for the backend server will still be necessary. See here for more details.
Client Access License Terms
User CAL: a Client Access License that is assigned to a specific person. The CAL cannot be transferred to another person on a frequent basis. (I am not aware of any Microsoft products that use a “concurrent users” model where User CALs are shared within a pool of people.)
Device CAL: a Client Access License that is assigned to a specific device. Anyone using that device has access to the server while they are using that device. The CAL cannot be transferred frequently from one device to another.
Additive CAL: a Client Access License that is added on to a base CAL to provide the end user with more functionality. For example, a Standard CAL for Exchange is needed for all users or devices that access the Exchange Server and it provides a basic set of functionality. An Enterprise CAL for Exchange is an additive CAL and provides additional functionality. So, for every user or device you want to provide with enterprise features, you will need to purchase a Standard CAL and an Enterprise CAL.
Virtualization Rights: the right to install and use the product in a virtual environment.
Server Mobility Rights (a.k.a. vMotion Rights): the right to move a virtual instance of the product from one physical host to another. For more information on this topic, see here.