Again, making a guess here. Microsoft has been trying to get Windows and Office installs easier for the *average* user. Allowing the install to make changes is easier than you entering a key.

You may want to look here. The process may be different than what you experienced. http://www.microsoftstore.com/store/msusa/en_US/cat/Office-365-Renewal/categoryID.68289700

>If this is the only way, I will first make a good backup of the entire PC. Then will see. Too back I cannot purchase and just enter some king of key, as it is done with many other software.
>Thank you.