The CIE does need you to have purchased Corona, so the second machine will need the license server installed (or you will have to have the license server set up on a network). But the GUI license used by the CIE is not the same as the one used by Corona, which means you can have Max open and be using Corona GUI and rendering there, while another machine has the CIE opened and in use, with just one subscription for Corona and no additional purchase.