Abstract: Scheme for switching a computer system (21), which is connectable via a communication interface and a network (22) to a server module (23), into a special mode of operation. The computer system (21) comprises a software component (26) for sending an identifier (w) assigned to the computer system (21) via the communication interface and the network (22) to the server module (23). In response, the software component (26) receives a token (S), issued by the server module (23), whereby the token (S) comprises a credit (C). In addition, the computer system (21) comprises a trusted hardware component (25) storing the identifier (w) and comprising a credit counter (44) with a credit which is automatically exhaustible step-by-step, and which is updateable with the credit (C) received from the server module (23). The computer system (21) has a trigger unit for switching the computer system (21) into the special mode of operation, e.g.