Let me start off by saying I've never actually experienced laser hair removal myself.

However, I have a friend who did it, and another one who just checked out a few places and methods. It is my understanding that its never permanent. Basically after 10-12 times you notice a big difference in the density and texure of your hair, but you need about 20 treatments which take about a year all together to have all the hair removed from a certain area.

As the hair growth depends on physicality and hormons, you can remove it all at a certain age, and then at an older age - your hormons change and you can grow back the hair. If you're looking for numbers its 80% success. (thats what I've read).

 Good luck! :)