The STA ticket is generated when you try to launch a resource through a NetScaler gateway. The STA ticket is included in the ICA file. When Client launches the ICA file, the Gateway redeems the ticket to allow remote access. For security reasons, this ticket is only valid for a limited length of time. Follow the steps below on all Delivery Controllers to modify the STA Ticket Lifetime:

1. Take a backup of HKLM\Software\Citrix\DesktopServer.
2. Create the below key:

Caution! Using Registry Editor incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

How To Change STA Ticket Lifetime