XLSApp is middleware software between Excel and your Client (Multicharts, Metatrader etc). Your Client is using DLL to access XLSApp and XLSApp is coordinating the communication between Clients and Excel. XLSApp is designed to run on your computer with low resource needs. You should run XLSApp before you call XLSgate functions. Moreover XLSApp is designed to be a debug instance for you. XLSApp will show you debug informations, such as Warnings, Errors.
You can run XLSApp in background for very long time. It has been optimised for long-term runtimes and to use very low resources. It will use any resource only if DLL is communicating with it, otherwise it will use very low resources. It is very important to know that XLSApp is hearth of XLSGate, so it should run before you access your Trading Application. We recomment to keep it running or even Autostart it.