One way to do this is to control how many copies of an application are allowed to run at any point in time using a license management system. This way we only need to buy as many copies of a package as is actually needed at any point in time and not necessarily one for each station. There are several ways that access to software applications can be controlled. The easiest is having the application reside only on the server and be run from the server. Windows NT has the ability to control the number of people that have access to any specific directory, thereby controlling how many copies of a specific application are available at any point in time.
Wrappers Metering the software using tools loaded only on the server is the easiest to install.
The advantage of methods that require that each client run a portion of the code is that applications may reside on the clients as well as the server. This is preferred especially where the client machine resides off campus. This type of tool can still track usage even if it is not run on the network. Software suites like Microsoft Office also complicate metering of individual applications. One does not want to tie up a license for the entire suite if only one application is being used at a time.