It is the number of subpages on your domain that determines what premium subscription is needed. You do not need to make an active choice, since the correct subscription will be determined by the Cookiebot scanner based on the number of subpages.
Please note that you will need a subscription for each of your domains and each of your subdomains. It is not possible to combine several domains under one subscription (it is possible to handle multiple domains from one account but that has no effect on the number of subscriptions needed).
Last updated: 4 May 2018