Such functionality for flat fee for a product is not supported. I have logged a feature request in our Feedback portal
where you could vote for it.
Thank you for your feedback.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items