Citrix XenApp Licensing: How It Works

Citrix XenApp (now known as Citrix Virtual Apps) is a platform for managing and hosting virtual applications on the cloud, on premises and in hybrid datacenters. The Citrix XenApp licensing model requires acquiring concurrent licenses that allow users on multiple devices to run multiple instances of virtual applications all at once.

Citrix XenApp and the Required Microsoft Licensing

Citrix XenApp was renamed Citrix Virtual Apps in early 2019. It comprises the virtual applications component in the Citrix Virtual Apps and Desktops product suite, with Citrix XenDesktop being the virtual desktop component. However, Citrix XenApp remains widely used as the name of the platform.

Citrix XenApp allows hardware with supported Windows Server OSs to be installed with applications that can be accessed from anywhere using any device. The host servers take care of performing all application functions, with Citrix Receiver being the only component required to be installed on client devices that will run the applications.

Organizations are required to have Microsoft Remote Desktop Services client access licenses (CALs) to use Citrix XenApp. Windows Server and SQL Server licenses are also required for setting up Citrix XenApp.

Citrix XenApp allows an unlimited number of host servers for its virtual applications. Thus, organizations are free to install virtual applications on multiple servers. XenApp tracks only the user devices that connect to its servers and assigns licenses to these devices accordingly.

Citrix Licensing Requirements and Functionality

To help organizations make better sense of Citrix XenApp licensing requirements, Citrix provides a common licensing model anchored on two key components, namely:

Citrix License Server: Available on Windows and Unix, this component issues the license files to devices accessing your Citrix XenApp environment. Citrix uses the concept of a grace period to allow access to Citrix XenApp, even if license files have been used up.
Product licenses: These are divided into user/device and concurrent licenses. User licenses are ideal for users with multiple devices, device licenses are ideal in cases where multiple users share the same device, and concurrent licenses are best for scenarios where multiple users need simultaneous access to an application.

Computers installed with the license server component can either be dedicated solely to or have other purposes aside from license issuance and management. Larger organizations may choose to deploy several license servers at once to streamline operations. Organizations can also upgrade or downgrade licenses as needed.

License servers come with Citrix Licensing Manager, which helps administrators view and track licenses, import additional licenses, create usage reports and manage settings on the license servers. It also generates alerts when your supply of license files are running low and need replenishment.

The typical Citrix XenApp environment works as follows:

User devices connect to the Citrix XenApp servers hosting the applications they need to run.

Citrix XenApp checks License Server for available licenses for the user devices.

Citrix License Server assigns licenses to the user devices.

The applications start running on the user devices.

From a perpetual license model, Citrix transitioned to a subscription license model for all its products, including Citrix XenApp, in late 2020. However, licenses purchased prior to October 1, 2020 are not covered in this new model.

Citrix Concurrent Licensing Model

In a typical scenario, a user device is granted a concurrent license when it runs an application. That Citrix XenApp licensing becomes available for use again when the user device stops using the application. Thus, a concurrent license is not tied down to a specific user or device.

Citrix XenApp supports only concurrent licenses. Thus, users are free to access virtual applications at the same time and from any device.

However, concurrent Citrix XenApp licensing are twice as expensive as user/device licenses. Thus, to prevent overspending on concurrent licenses without reducing productivity, it is imperative to plan your license requirements carefully. For example, an organization that has only half of its 100 users logged to an application at the same time may want to get no less than 50 concurrent licenses to ensure continuous access for its users.

License Grace Period Uses

In Citrix environments, the Citrix XenApp licensing servers allow temporary access through a predefined grace period when the licenses have been used up. Grace periods as applied to Citrix products are classified into two types, namely:

License overdraft: Products come with 10% more licenses so that users won’t be denied access when the purchased number of licenses have been used up.

Supplemental grace period: An additional 15 days, running consecutively, is allotted to allow continued access in case purchased licenses and the 10% license overdraft have all been used up.

Only the 15-day, supplemental grace period is applicable to Citrix XenApp. While this grace period is in effect, users are allowed to continue using the Citrix product. Once the grace period lapses, users will no longer be allowed access. Only after additional Citrix XenApp licensing have been procured will user access be restored.

Parallels RAS Provides a Simple Single Licensing Model

Parallels® Remote Application Server (RAS) uses an all-inclusive, single-license model to provide enterprise features such as application and desktop delivery, load balancing, monitoring and reporting, universal printing and Federal Information Processing Standards (FIPS) 140-2 encryption. Since there are no third-party add-ons to maintain, organizations also do not have to pay for anything extra.

The comprehensive license model offered by Parallels RAS reduces the complexity often associated with license maintenance, allowing organizations to scale their environments on demand and without any hassle. In addition, the solution requires minimal knowledge to configure and maintain, thereby reducing your learning curve. Full training on Parallels RAS is also provided for free, further reducing your expenses.

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