> Languages and APIs > The ILOG CPLEX Callable Library > Architecture of the ILOG CPLEX Callable Library > Licenses

ILOG CPLEX runs under the control of the ILOG License Manager (ILM). Before you can run any application program that calls ILOG CPLEX, you must have established a valid license that it can read. Licensing instructions are provided to you separately when you buy or upgrade ILOG CPLEX. Contact your local ILOG support department if this information has not been communicated to you or if you find that you need help in establishing your ILOG CPLEX license.