BackOffice Robot, Orchestrator and Windows Client

I’m deploying a project in which I can connect to a Virtual Machine, which is exactly a Windows Client under a Windows Server 2008, where I’ve “installed” a robot managed by Orchestrator.
When the session is on, I don’t think I have any problem.
But, what happen when I close the session or when I don’t run any session? Is the robot running or failing?
Do all activities run or Image Recognition and OCR fail?

Thank you in advance.