License management class: Generate and validate license serial numbers

=============================================================
Script Name               : license management class
Auther                    : Payam khaninajad
Contact                   : [email protected]
Follow me on twitter      : http://twitter.com/khaninajad
Location                  : Iran-Azarbayjan 
Year                      : 2010-12-19
Version                   : 1.0
=============================================================
This class can be used to protect the script from unauthorized use.
this script you can force users to buy your script . 
With this class you can identify nulled scripts and report .
In this example, you can use three ways to do this:
1.Local
2.curl function
3.AJAX/jquery