Kurt,
The License Policy that we know today, about one copy per one machine
per one license, was introduced with Windows 3.1. Which for the
majority of users represents the start of mass market Windows usage.
It is detailed in Microsoft Knowledgebase article Q83926, which is
still available online at
http://support.microsoft.com/?id=83926
copied below for reference
Windows 3.1 Licensing Policy Allows for One Copy per License
The information in this article applies to:
a.. Microsoft Windows 3.1
b.. Microsoft Windows 3.11
This article was previously published under Q83926
SUMMARY
The licensing policy for the Microsoft Windows operating system
version 3.1 is different from the licensing policy for Windows 3.0.
The Windows 3.1 licensing agreement allows for only one installation
per license.
MORE INFORMATION
Under the licensing agreements for Microsoft applications software and
Windows 3.0, if the software is permanently installed on the hard
disk or other storage device of a computer (other than a network
server) and one person uses that computer more than 80 percent of the
time it is in use, then that person may also use the software on a
portable or home computer.
However, Windows 3.1 is considered systems software and therefore
follows the same licensing agreement as MS-DOS (that is, you must
purchase one copy of the software for each machine).
The following is a copy from Grant of License section of Windows 3.1
license card:
Grant of License. Microsoft grants to you the right to use one copy
of the enclosed Microsoft software program (the "SOFTWARE") on a
single computer. The SOFTWARE is in "use" on a computer when it is
loaded into temporary memory (i.e., RAM) or installed into permanent
memory (e.g., hard disk, CD-ROM, or other storage device) of that
computer. However, installation on a network server for the sole
purpose of distribution to one or more other computer(s) shall not
constitute "use" for which a separate license is required.
All Microsoft license agreements are version-specific, meaning that
they apply only to the version of the product that you acquired with
the license. If you upgrade from Windows 3.0 to Windows 3.1, you only
have one license for Windows. The Windows 3.1 license replaces the
Windows 3.0 license