05047928 is referenced by 382 patents and cites 20 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.

Title
Billing system for computer software
Application Number
922689
Publication Number
5047928
Application Date
January 3, 1989
Publication Date
September 10, 1991
Inventor
John D Wiedemer
930 W. Forest Dr., Houston, 77079
TX, US
Agent
Quarles & Brady
IPC
H04L 9/00
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