as i understand it, the programme is downloaded to your computer once you have purchase dit. you don't actaully get discs. This means that it only works on the computer it was downloaded to.
Assuming you are a budding wannabe, then the £69.99 cost of the programme is a drop in the ocean when you think about how much you will be spending overall.
my advice is don't bother buying it. There was a post on here a few months back mentioning that you are cheating yourself and others. Aptitude is exactly that - either you have it or you don't. No point practising pointless motor-coordination tests in order to be accepted, only to find out that you really can't use a yoke, rudder, and throttle whilst listening to ATC.