I am currently launching a SaaS web application. I want to have subscription packages such as: Premium: 5 users, 20 widgets, 20 MB storage Basic: 2 users, 10 widgets, 50 MB storage I want to allow companies to upgrade and downgrade packages at any time. The problem I am having is what if the company is on the premium package and has 5 users, 20 widgets, and wants to downgrade to the "basic" package. How do I handle that? Do I flag an error and say "You cannot downgrade" or do I take them to a page to remove the "extra" users and widgets? Any advice or examples of how other companies do it would be great!!