It automatically detects what platform you are calling form. If you are using the Macs here, you will get a Macintosh Software listing. Look down on the opening page for the buttons to change platform. These are public domain programs that you can use with no problem. These give you an insight into a larger program.
Some demos only work for a short period.
Others only show you certain features. Those of the latter type may be all you need. Remember, you are not really trying to USE the software, you want it to be the stimulus of a language learning activity. The demo may be more than enough. This is software that you should pay for if you plan to use it a lot.