Hi, and welcome!
@guplasse said in Qt for commercial Use:
If i build my sofware with QT Open Source Licence, can i sell it ?
Yes, you can.
if yes what are the conditions ?
These are specified by the license. (Note: Some Qt modules are available under both the LGPL and GPL licenses; other modules are only available under the GPL license)
How should I mention that I am using QT ?
2 good places are:
In your software's documentation In an "About" dialog that is popped up by the GUI. (This is often placed under the "Help" menu)if i have to buy QT, can i really do whatever i want with the source code ?
Yes, you can.