i wanted to make a registration key for my installer that just run on one computer with that key , once.
i mean that after installation it can't be installed on another computer....
You should use a user specific customized license which generates your license key using the computer id of the target machine. To do that you should enable "Computer Specific - license will be valid only on the system from which it has been requested." option from "Registration" tab.
Please note that the support that me colleague pointed you towards has not the purpose to limit the users from installing the setup package.
The support he guided you to use it allows you to integrate in your application a trial mode, i.e. try/buy. This mechanism has a customizable template for the license key
the user can receive, this is where you define the custom format using the computer ID, so the license key received will work only that machine.
The users will be able to install the application but will not be able to register it without the special code given by you.
We do not have any out of the box support for your request.
As another workaround solution you can try to create and develop your own custom actions which will check the environment on which the setup runs and block/allow the installation.