All software products are subject to certain licensing conditions. There are mere usage licenses which basically exist in the form of a "sheet of paper" as well as licenses which use technical methods to monitor compliance with the license conditions.
In the case of mere usage licenses the license holders accept the terms and conditions of the contract by signing the contract or simply using the software and thereby commit themselves to adhere to those conditions. The adherence to the terms and conditions of the contract will not be controlled by technical means. Usage licenses are offered in various forms. Some of the most widely spread licensing types in this area are:
- Free Software: The software may be used - usually free of charge - by anyone who accepts the terms and conditions of the contract.
- Single-User License: Many software products must be licensed for every PC they are used on. One license cannot be used on several PCs.
- Concurrent Use License: Authorise the use of the software on any number of computers, as long as you do not use it on higher number of computers simultaneously than the number of purchased licenses.
- Campus, Fakulty or Institutional Licenses: The software can be used on every PC of the institution that signed the contract (e.g. University).
Many commercial software producers make use of control mechanism which monitor if the software is used in accordance with the terms and conditions of the contract. Basically there are the following possibilities:
- Nodelocked License: The software is licensed for a certain computer and is bound to it by a hardware ID.
- Named User License: The software is bound to a certain user and can be used on any PC by exactly this user.
- Floating License, Concurrent Use License: The software is licensed for a certain number of simultaneous accesses. The type of computer/operating system is usually not determined.
Specifics of Floating Licenses/Concurrent Use Licenses
Floating Licenses/Concurrent Use Licenses can especially be found in the area of scientific application packages or programming tools which are used extensively at RWTH Aachen University.
As Floating Licenses/Concurrent Use Licenses are not bound to certain systems, the number of simultaneous accesses is controlled by so-called license servers. Those run a process for every software configured in this way that is aware of the number of accesses and if necessary other frame conditions of the software package. During the run time the application software connects - cryptographically secured - to this process to receive clearance to run. If the number of simultaneous accesses is exceeded the user will receive a notification that all licenses are currently in use.
Compared to the other types of licenses, Floating Licenses/Concurrent Use Licenses have the advantage of the highest flexibility. The Software can be used on any number of PCs and the only condition is a network connection to the license server. Some software products additionally offer the possibility of borrowing network licenses and using them offline for a certain number of days. In this case the software can also be used without a permanent connection to the license server.