The invention relates to a method for extending the functionality of an electric welding apparatus which comprises a programmable control unit and an input device. In order to provide the user with greater latitude for a desired functional extension while nevertheless ensuring that unauthorised functional extension can be prevented, the invention proposes that a control command for a desired functional extension is issued to the control unit and the control unit uses the control command or the functional extension to generate an apparatus code which is transmitted to an external verifying facility, wherein the external verifying facility uses the apparatus code to verify entitlement to the functional extension and, if entitlement exists, generates an external activation code which is transmitted to the control unit, and wherein the control unit verifies the validity of the external activation code and, if it is valid, implements the functional extension. A welding apparatus for carrying out the method is also proposed.
