You must have an original Norton 360 product key in order to activate it. Activation can be done during installation, or after you installed Norton 360. If you choose to activate after installation, make sure you do it quickly, otherwise Norton 360 will stop working after several days.

To activate after installation start Norton 360 and open the Main Window, click My Account » Activate Norton 360 » provide the 25-character product key. It it is located on the back of the CD envelope or in your order confirmation email if you purchased via Symantec Online Store.

Learn more about Norton 360 activation.