05155680 is referenced by 198 patents and cites 22 patents.

A computer software security and billing system is disclosed in which the application program is enciphered in accordance with an algorithm driven by a numeric key. The user's computer is provided with a hardware security module and a removable billing module, both of which carry unique codes. A security program accesses the application program and also writes information about billing into the billing module. The billing module is periodically replaced so the user can be charged based on amount of usage of the software. The security system is also capable of operating to provide data and program security independent of the billing function.

Title
Billing system for computing software
Application Number
922689
Publication Number
5155680
Application Date
April 27, 1989
Publication Date
October 13, 1992
Inventor
John D Wiedemer
Houston
TX, US
Agent
Quarles & Brady
Assignee
Signal Security Technologies
TX, US
IPC
G06F 15/00
View Original Source