The following article will go through the step-by-step process of install the Citrix License Server component required for all XenApp and XenDesktop implementations. Without this component XenApp and XenDesktop simply won't function.
Insert the Citrix XenApp/XenDesktop 7.9 installation media and click on Start next to either XenApp or XenDesktop depending upon, which product has been purchased or being evaluated.
Click on Citrix License Server under Extend Deployment.
Accept the license agreement and click Next.
Leave Configure firewall rules set to Automatically and click Next.