Depending on the service plan, a number of prepackaged applications can be available to Plesk users. You can install the apps on your own sites as well as provision them to your customers.
When setting up a hosting plan, you can select which of the apps should be provisioned to customers:
To provide all available applications, on the Permissions tab, select the option Access to Application Catalog.
To provide only selected applications, on the Permissions tab, select the option Access to Application Catalog, and then go to the Applications section and select the option Provide only applications that I select. Use the button >> to add the selected applications to the plan.