A method and a device for starting limited-time licenses for a telecommunication system in a controlled manner in which the system comprises a number of IP terminals. The licenses acquired by the respective customer for the telecommunication system are downloaded from a central license server via a network such as the internet. A date and a time, and thus an activation time period, are configured via a browser dialog using the web-based management component which is connected to the network (e.g. the Internet) for the purpose of an activation the first time the telecommunication system is started, whereby the maximally allowed use time for using the licenses at no charge is set. After the maximally allowed use time expires, the use of those licenses for which no right of use has been acquired is prohibited