I bought/installed Help Desk on Production SharePoint.
I want to install Help Desk on sandbox SharePoint(Testing purpose).
The sandbox SharePoint is located on same domain but different machine.
How to install Help Desk on sandbox?
Since you use another WFE-server for your sandbox SharePoint, it should have a separate license. Please ensure that there is no purchased production license on the WFE-server for sandbox SP. If there is no the one, you could purchase a development license for it. To install HelpDesk, please follow instructions from this article.