Recently, many educational institutions have acknowledged the importance of making laboratories available on-line, allowing their students to run experiments from a remote computer. While usage of virtual laboratories scales well, remote experiments, based on scarce and expensive rigs, i.e. physical resources, do not and typically can only be used by one person or cooperating group at a time. It is therefore necessary to administer the access to rigs, where we distinguish between three different roles: content providers, teachers and students. This paper reports on a conceptual model and technical design of a rig booking system that provides mechanisms for content providers and teachers to control and grant access to on-line remote laboratories. The design of the booking system is based on a requirements analysis carried out by the EC funded LiLa project in cooperation with international partners from the Global Online Lab Consortium, GoLC.