The computer science department at our university has a Matlab licence.
In case you don't know what Matlab is, it's a "numerical computing environment and fourth generation programming language" [wikipedia]. Scientists everywhere use it in their work, and our school prepares us for that by requiring us to write Matlab code.
Now, for a concrete example: Say I want a random number from a normal distribution. I fire up Matlab at the computer lab (or, SSH into the school server from home), and type:
>> normrnd(0,1)
Matlab promptly responds:
??? License checkout failed.
License Manager Error -4
Maximum number of users for Statistics_Toolbox reached.
Try again later.
To see a list of current users use the lmstat utility or contact your License Administrator.
Troubleshoot this issue by visiting:
http://www.mathworks.com/support/lme/R2009b/4
Diagnostic Information:
Feature: Statistics_Toolbox
License path: /home/tko/pviktor/.matlab/R2009b_licenses:/usr/local/matlab2009b/licenses/license.dat:/usr/local/matlab2009b/licenses/network.lic
FLEXnet Licensing error: -4,132.
>>
Easy, isn't it? Compare that to Octave:
octave:5> normrnd(0,1)
ans = -0.71192
