Once you have downloaded the software from your Trados Studio account, you should activate your licence with the provided code (subscriptions models do NOT require activation codes).
When starting Trados Studio, you will see a notification of the remaining number of days in Trial Mode, or if the trial period has already expired, you will be prompted to activate immediately-
The 'activation code' can be found under the Licenses section of your account.
Trados Studio is now activated.