> An application using Qt Commercial must not communicate with any another application using Qt LGPL-3.0 or Qt GPL, if both applications run on the same device.

> An application using Qt Commercial must not communicate with any another application using Qt LGPL-3.0 or Qt GPL, if both applications run on the same device. This seems crazy to me. How could you ever enforce this? If I buy some Software which uses the Qt Commercial Variant internally, you would have to make sure that it doesn’t support any standard IPC Protocol, that a potential LGPL Qt program could use too. The default answer to the question if you should use LGPL or commercial should always be LGPL. Unless you really really have to use Qt on an embedded system. Otherwise the Qt Company will come for you… Edit: One of the bigger Problems with Qt6 is, that there are no more non-commercial LTS Versions. This forces some bigger companies to buy out of fear and/or policy. Even if they don’t build embedded systems. And if you bought in once it is very hard to get back to the LGPL variant.