When you set up the appliance it should ask you to enter an Activation Code (License). However, if it already has a license and this expired and you purchased a new one (extension) then it should automatically sync, if this isn’t happening please open a case with support to get this investigated.
There are no specific steps, as mentioned during the initial configuration it’ll ask you to enter the Activation Code, if you’re already in the main menu, it means the Activation Code was entered before, in your case I think you’re already seeing the main menu, which won't have an option for you to enter the license, you’ll need to check with Customer Care or your Account Manager.
Where did you get this appliance from?
Sophos Appliances - Email and Web
You will get a separate email for each type of appliance purchased (e.g. web appliance and/or email appliance), providing setup instructions and required activation code(s).
The activation code is applied during the setup wizard only. If you have passed through the setup wizard, there is no way to change the activation code unless you sign up for trial. There will be a red link at the upper left-hand corner where you can change from trial to a legitimate one provided that you have chosen the 30 day trial during the setup.
Notes:
If the account manager gave you a temporary activation code (can be good 30 days or more) beforehand and you entered it in the Activation Code option, then you will have to either re-image or RMA the appliance or check with the licensing team the validity of the activation code.
Application of the activation code is only relevant for a new installation.
For renewal, license details are updated automatically. If not, authorized contact will need to contact Customer Support with the following information:
The serial number of the appliance with an expired license
