We run a license server for Mathematica. If you wish to use it, just supply the server’s name mathlm.cpfs.mpg.de to Mathematica upon configuring licensing. Note that we have a limited amount of licenses, thus in favor of your colleagues it is important that as soon as you don’t need Mathematica anymore, please quit the application.
Mathematica for Macintosh can be obtained from me. For Windows and Linux PCs, please contact the IT service. The full list of supported systems can be obtained from Wolfram Research.