Abstract: A central program comprising a EI sub-program for providing identity information of the rightful user thereof for accessing a network central computer to obtain service(s) or software product(s) or alike, in which a secure operation on an account of the rightful user for payment therefor involved; and a AS sub-program for using the existence of the EI sub-program in a computer as a precondition for authorising use of those software products obtained on that computer. The central program is for managing the use of the individual sub-programs therein so that the AS sub-program can be protected from being copied individually.