Installation with a key from a physical card

Norton asks me in a no-reply e-mail to update my payment information.  My last update comes from Fnac where I bought a physical card with key.  I installed Norton several times because the installation is never complete or whatever.  I understand very well why, the installation program never asks for the key and I don't know how to get the key in the program when it doesn't ask for that. 

At the moment I have no problems with the installation.  Can somebody give a clarification why you can install the program without key?