Well, most of QT libraries are LGPL, therefore you don't need a commercial license for a non open source project as long as you dynamic link against the Qt library and don't static link against it. On Windows it is easy to pack an application with all shared library dependencies, all you need is copying the shared libraries (*.dll files) to the executable directory. Unlike on Unixes, on Windows, the loader searches first the dependencies at the executable current directory or in directories listed in PATH variable.
Other alternatives are: WxWidgets; MFC - Microsft Foundation Classes that has GUI builder in Visual Studio IDE; Borland VCL - Visual Component Library; Sciter library which allows creating the GUI in html and has a C API. Another way is to build the application on top of Win32 GUI API that is well documented and has lots of examples, unlike X11-Xorg (X Windows System) used on Unixies, such as Linux distributions or BSD variants.
Other alternatives are: WxWidgets; MFC - Microsft Foundation Classes that has GUI builder in Visual Studio IDE; Borland VCL - Visual Component Library; Sciter library which allows creating the GUI in html and has a C API. Another way is to build the application on top of Win32 GUI API that is well documented and has lots of examples, unlike X11-Xorg (X Windows System) used on Unixies, such as Linux distributions or BSD variants.