Method for operating a control device of an infotainment device of a motor vehicle for activating functions, wherein the control device comprises an integrated circuit, characterised by the following steps: - a user requests an activation of a circuit function and/or a circuit region of the integrated circuit by means of a user input; - the infotainment device creates a corresponding request signal and sends this to a central computer of a manufacturer of the infotainment device or the motor vehicle; - the central computer receives the request signal and checks a permissibility and applicability of the requested activation; - the central computer transmits a signal to a central activation computer of a manufacturer of the control device; - the central computer sends a predetermined communication signal to the infotainment device; - on receipt of the communication signal by the infotainment device the latter is set into a mode in which direct communication is possible between the control device and the central activation computer; - when the infotainment device is in this mode the infotainment device sends a signal to the central computer, which signals a communication readiness of the control device; - the central computer directs the central activation computer by means of a signal to send a control signal to the control device; - the central activation computer of the manufacturer of the control device generates a control signal to the requested activation and signed by means of a cryptographic method and sends it to the control device; - the control device checks the signature of the control signal as part of an authenticity check by means of the cryptographic method; - when the control device confirms the authorisation of the central activation computer a control of the control device is permitted; - the central activation computer controls via a protected connection a function control unit of the control device by means of the control signal; - the function control unit processes the control signal and changes at least one entry relating to an activation state of a respective circuit function and/or a respective circuit region of the integrated circuit of a function register unit; - by means of the integrated circuit the respective circuit function and/or the respective circuit region is activated for use according to the at least one entry of the function register unit; - by the function control unit an confirmation signal is sent to the central activation computer, which communicates that the activation for use has been performed by changing the assigned entry in the function register unit; - the central activation computer transmits a signal to the central computer in order to confirm the sending of the control signal and the activation; - the central computer sends a reference signal to the control device to confirm the completed activation. - a user requests an activation of a circuit function and/or a circuit region of the integrated circuit by means of a user input; - the infotainment device creates a corresponding request signal and sends this to a central computer of a manufacturer of the infotainment device or the motor vehicle; - the central computer receives the request signal and checks a permissibility and applicability of the requested activation; - the central computer transmits a signal to a central activation computer of a manufacturer of the control device; - the central computer sends a predetermined communication signal to the infotainment device; - on receipt of the communication signal by the infotainment device the latter is set into a mode in which direct communication is possible between the control device and the central activation computer; - when the infotainment device is in this mode the infotainment device sends a signal to the central computer, which signals a communication readiness of the control device; - the central computer directs the central activation computer by means of a signal to send a control signal to the control device; - the central activation computer of the manufacturer of the control device generates a control signal to the requested activation and signed by means of a cryptographic method and sends it to the control device; - the control device checks the signature of the control signal as part of an authenticity check by means of the cryptographic method; - when the control device confirms the authorisation of the central activation computer a control of the control device is permitted; - the central activation computer controls via a protected connection a function control unit of the control device by means of the control signal; - the function control unit processes the control signal and changes at least one entry relating to an activation state of a respective circuit function and/or a respective circuit region of the integrated circuit of a function register unit; - by means of the integrated circuit the respective circuit function and/or the respective circuit region is activated for use according to the at least one entry of the function register unit; - by the function control unit an confirmation signal is sent to the central activation computer, which communicates that the activation for use has been performed by changing the assigned entry in the function register unit; - the central activation computer transmits a signal to the central computer in order to confirm the sending of the control signal and the activation; - the central computer sends a reference signal to the control device to confirm the completed activation.