Hello mayuresh,
I believe you are asking the wrong question at the wong place.
This is not M$ world. The software is given for fukat(free) and the support is only charged.
the user has a right to modify the original program and redistribute it.

This is linux.
please do not change the L to Pound sign.

Anand

Original message from mayuresh follows....

how do s/w vendors ensure that a customer who buys a
CD can use it to install the s/w only on his computer
and if he takes a CD dump, the second CD will be of no
use to anybody else?

i guess there must be many techniques to do that but
which one is used frequently?

thanks a lot..

mayuresh kulkarni