3.8. Do I need to worry about LGPL when using a commercially licensed version of Qt?
Usually, not. When using the commercially licensed version of Qt, we provide almost all of Qt under a commercial license terms.
A few modules in Qt, however, use code from the WebKit project licensed under LGPLv2.1. These modules are Qt Script, Qt WebKit and Qt WebEngine. So when using these modules, you will need to fulfill the license obligations of LGPLv2.1 (but not LGPLv3).
As a commercial license user, in practice, you only need to consider license obligations of LGPLv2.1, and only if you make use of Qt WebEngine or Qt WebKit .