Why is Qt Free Edition not distributed under the GNU Lesser General Public License (LGPL)?
The LGPL is designed to “permit developers of non-free programs to use free libraries” (quote from the LGPL). In other words, if Qt Free Edition were LGPL’d, companies would not have to purchase our commercial editions in order to make commercial/proprietary software, they could just use the Free Edition, free of charge. That would mean Trolltech would not get the revenue necessary for improving and extending Qt. Note also that the Free Software Foundation discourages the use of the LGPL.