In the current implementation, web users cannot save their session configuration. However, when the user creates a new virtual desktop, disconnects from that web session (for example by closing the web page) and connects again, he/she should find the previous session listed in the list of available connections. Double click on it to re-open that session.
The same should happen if the user closes the session by clicking on the Disconnect button from NoMachine menu -> Disconnect panel (ctrl+alt+0 or click on the page peel to open the menu) or by making system logout. If the user instead makes system shutdown the virtual virtual desktop session is terminate and cannot be re-opened later.