We believe in the Free Software movement where using software comes with certain rights, but also certain obligations. Use of open source licensing gives users four primary degrees of freedom when using Qt applications or devices:
The freedoms are non-negotiable and absolute, the freedoms cannot be enjoyed selectively or partially, you also need to pass them to your users.
The Free Software community has thrived because of these rules, but there are also developers who never intend to observe or cannot comply to these rules, and thus should get a commercial license. The Qt Company exists to support both sets with the dual offering.