A simple guide to Microsoft server licenses


If you are trying to choose a Microsoft server for your organization, you may be feeling a little overwhelmed. There are lots of elements to consider when deciding which server will work best for your company. Have you tried looking at various server editions and licenses and felt a little bit confused? If concepts like CAL’s (client access licenses) and cores are leaving you feeling a little befuddled, never fear. We’ve created a simple guide to Microsoft servers and licenses that will explain various terms and concepts making your decision much easier.

A simple guide to Microsoft server licenses

A few definitions

  • Core

A core in IT terms is similar to the mind of the CPU, or central processing unit, of the computer, where are instructions are processed. The core does the processing of all instructions sent to the CPU.

A server core is an installation option from Windows that allows the server to be run with fewer features. Only the essential core network services are run.

  • CAL

CAL stands for client access license. When you are working with a server network with multiple users, a CAL is often required to allow users to access the server legally. A User CAL is a license purchased for an individual. It can usually be used across a variety of devices. A Device CAL provides a license for only one device.

  • Per core licensing

CAL’s are not always required. In some instances, called per core licensing, you will receive a certain number of licenses for a certain number of cores. If using this model you will need to calculate the number of licenses needed. Simply add up the number of cores per processor on the server then multiply this number by the processor core factor.

  • Virtual Machine

A virtual machine, or VM, is a self-contained operating environment that acts just like a separate computer. When certain VMs are run, they have no access or connection to the host operating system. This means the application or VM can be run regardless of what hardware or software is already on the computer.

Licensing Models

There are three main types of licensing models:

  1. Per Core/ CAL
  2. Server/ CAL
  3. Management servers

Why are there difference license types?

When Windows introduced its Server 2016 Standard Edition and Datacenter edition, they also introduced a new licensing model. This model is based on the server’s cores, unlike previous models that were based on the processors themselves. With this new update, CAL’s are still required.

When you purchase a single operating system license, you will receive a license that allows you to install this operating system onto the server. However, this one license does not cover multiple users or devices. To legally provide operating systems for more users and/ or devices, CAL’s will need to be purchased.

Explaining CAL’s in more detail

A Windows Server CAL allows clients to use the Windows Server legally. These are the licenses that legally permit more than one user or device to access and use all of the features and services of the server operating system.

This system is a way of monitoring the capacity used and to ensure that as a company grows, the price of its operating system increases accordingly. The more users and devices, the more they will have to pay.

User CAL’s versus Device CALS’s

  • User CAL’s

A single User CAL allows a single user to access the Windows Server from as many devices as they choose.

This option is ideal for companies whose employees will need access to the network from a variety of locations and devices. If your employees work from home or need to travel, or even if they need to use their own devices, this is the option for you.

  • Device CAL’s

A single Device CAL allows the Windows Server to be run on one device, which can be used by infinite number of users.

A simple guide to Microsoft server licenses

This option is ideal for companies in which one device will need to be used by multiple employees. If your company has shift workers using a hot seating workstation, this will make the most sense for you.

Tips regarding CAL’s

It’s crucial that your company stay up to date regarding new licensing rules and regulations. If you are adding lots of new users or devices, be sure to check you are still complying with the license rules. You may need to purchase more CAL’s.

Choosing a server edition

Servers tend to come in one of three editions – Essentials, Standard or Datacenter. Knowing the difference between the three types will help you decide which server software is the best choice for you.

  • Essentials Edition

The Essentials edition software has a pre-built-in integration with Office 365 hosted services, which makes in the perfect choice for you if you are planning to move to the cloud. Simple remote access to your computer and files is also possible with this edition. Finally, you will never need to buy additional individual user or device CAL’s, so the initial cost is all you will ever have to pay.

This is a CPU-based license, not needing or allowing CAL’s. This helps to make the installation process and the purchasing process very simple.

This edition is best for a smaller organization or company. Because it comes with a maximum number of users and devices that have server access, if you anticipate company growth, this option might not be best for you.

With this edition, you will be limited to 25 users or 50 devices. So, if you are planning on expanding your company in the next few years, you may find yourself needing to switch editions.

  • Standard Edition

This edition falls somewhere between the Essentials edition and the Datacentre edition. It offers lots of great features that aren’t found in the Essentials edition, at a slightly more affordable price than the Datacenter edition. This edition allows users to run two virtual machines. 

This edition is ideal for a company of medium size that don’t require more than two VMs.

The standard edition is a core-based license that requires CAL’s. This means you must purchase at least 16 core licenses per server. Core licenses are sold in packs of two. If your server has more than 16 cores, you must purchase the same number of core licenses as physical cores.

Company expansion won’t be a huge issue with this server edition as you can purchase more core licenses as you go. However, if you anticipate a future demand for more than two VMs, you may wish to consider choosing the datacenter edition instead.

  • Datacenter Edition

With the datacenter edition, the limitations of company size and number of available VMs will not be an issue. The main difference between the standard edition and this edition is that the datacenter can run more than two VMs.

This makes the datacenter edition the perfect option for you if you are catering for a medium or large sized company with a large IT department.

The license is core-based, and works in the same way as the standard edition. The main drawback to this edition is the cost. However, it will be worth choosing this option if you have a large or growing company, as switching will be less cost efficient in the long run.

Where to purchase your new Windows Server

There are a myriad of ways to get set up with a new Microsoft server and license. Hopefully this guide has helped you to decide which option is best for your particular situation. Using one of these Microsoft Product Discounted Activation Keys is one of the easiest ways to get started. Delivery is completed digitally and is guaranteed to happen within 24 hours of purchase. Plus, there are plenty of different options to choose from so you’re bound to find the perfect license model for you.

You can also pick up some other essential products at Imp Keys, including Microsoft Office, CorelDraw and Kaspersky. You can even buy a Microsoft Windows license suitable for one PC if you also need a personal upgrade.


Choosing the right Windows Server edition and the right type of CAL’s for your company’s needs is an important decision. The wrong choice could result in a lot of trouble for you and a lot of wasted company money. Think about the type of office you are trying to cater for. Think about how your employees need to work and how they will be accessing their files. Think about the size of the company and the potential for new hires or devices.

Once you’ve made your decision, be sure to keep up to date on your license fees and the number of users you have. Remember to purchase new CAL’s when needed. The final step is to enjoy your server once it’s up and running! The good news is, once all of the licensing hassle is taken care of, you are guaranteed to have a happy, functioning, efficient office.

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Lucy Bennett

Lucy Bennett is a Contributing Editor at iLounge. She has been writing about Apple and technology for over six years. Prior to joining iLounge, Lucy worked as a writer for several online publications.