A method of operating a computer system comprises the following steps:installing an executable main module of a program on the computer system, storing module data for the main module and/or for an additional module (A, B, C, D) of the program in the computer system, said stored module data comprising a license part required to determine the presence of the use authorization of the main module and/or of the additional module, and preferably also comprising an information part,evaluating the stored module data for acquisition of a further use authorization for the additional module (A-D) or for a further additional module (A-D), andproviding information for the acquisition of a use authorization as a function of the result of evaluation.