It is not a requirement that your customers sign up for a Premium subscription. As long as you invite them using either your unique reseller link or the ‘invite new customer’ button from your account, they will be automatically added to your reseller account. This is regardless of their type of subscription and it is possible to have ‘free subscription’ customers on your reseller account, under the retail model. You will not earn any administration fee on the ‘free subscriptions’. However, many resellers choose to offer this possibility to their customers as an added ‘customer service’.
Please also see: What happens when my customer accepts my invitation (reseller retail model) and signs up for a Cookiebot account. What type of subscription will he sign up for? When will he get an invoice?