Just a quick blog regarding a deployment model of Citrix NetScaler on Azure. There is an option to use subscription-based licensing for a deployment, meaning you pay by the hour it is running in Azure. See Deploy a Citrix ADC VPX instance on Microsoft Azure for more details.
This setup was chosen by a customer of mine which didn’t have any new licenses and wanted to migrate to such a model. This all worked fine but later the customer wanted to upgrade the license/throughput model of the deployment. Well after a quick discussion on the Citrix slack and support we came to the disappointing response this is not possible. The only way to upgrade is a redeploy of the instance with such a license model and restore of back-up or in case of an HA deployment break HA and redeploy it in that way.
Hope it helps!