Start the program, click the Help button, select the Enter Registration Serial Number from the menu and the "Registration" window will appear. Enter the registration information: serial license key number and as user name type in your name. Press the Register button.
If the information entered is correct, the registration will pass successfully. All limitations of the unregistered copy will be removed.
It is a good idea to save your key in a safe place to avoid loss of your registration (if you reinstall your system the registration key may be lost).