Slysoft license is not attach to computer. You can use single license on multiple machine. But make sure only one copy is active at a time. Slysoft recently became subscription based model. Means you can buy 1 to 4 years license. Also you have option to buy lifetime license which doesn't expire.
You can move license from pc to another pc as well. For example when you upgrade pc.
More Detail can be found slysoft forum.
If you interested in blu-ray playback or copy you may look into Anydvd HD which include function of both program in one package.
If you question feel free to post.
While at it I want to remind Slysoft is having sale until Sunday, April 19 2009 offering 20% discount on all products â€“ except upgrades and t-shirts.