In simple form, the policy is that each license purchased may be installed on one machine for use by one or more people, or installed by one person on more than one machine if that person is the only user. An example of the "one machine" license is a research lab where statistics software is installed on one machine, and used by several researchers. An example of the "one user" scenario is when software is installed by one person on her office machine and her home machine, and she is the only user.
With the advent of LAN-type servers, ITS implemented a multiple-user policy in which software purchased for use in a multi-user lab or office situation would cost no more than the full price for five users. When software is installed on a single server and more than five stations have potential concurrent access to the software from that server, an amount equivalent to five full license fees allows all the stations (up to 40) to have access.
Summary:
http://www.usc.edu/its/doc/statistics/help/pcsoftware/
and there is a link on that page to the official statement of the multiple-user/single-server LAN policy which is at:
http://www.usc.edu/its/doc/statistics/help/pcsoftware/labprices.html
Software is distributed by ITS through the User Services office in LVL Lower Commons (213/740-5555). Questions may be directed to them in person, by phone or via e-mail to <consult@usc.edu>