There are plenty of Qt open source users, who do not know that there is a commercial version of Qt. We ran into this frequently in different events, where people ask about commercial licensing options. Adding a button and menu item to Qt Creator to request a commercial version would make it clear that such a version exists.
Could we add a button to the welcome screen, which the user could use to navigate to a commercial version web page. Similarly, we could have a menu item in Help menu to request for a commercial version. Obviously, this button/menu item would not be visible for customers.