This information is only relevant to customers with perpetual licences. Subscription licenses (i.e. those purchased for a set time-period such as one year) do not require activation codes.
In order to use a new release of the software the license must first be activated. This is completed using an Activation Code, which will be issued to you by your distributor.
If you own a perpetual software license, when you run a new release of the software for the first time you will be asked to provide the Activation Code via the Software Activation window. This is used to activation your license for the new release and will only need to be completed once for each license that uses the new release.
You need to enter the Activation Code into the field provided, either manually or by Copying (Ctrl+C) and Pasting (Ctrl+V) from an email.
Your Activation Code will be provided by your distributor, normally along with the software release itself. However if you believe you are licensed to use the new release and have not been provided with an Activation Code please contact your distributor or use the email facility on the activation window to send a request for your code.