Which license do I need for developing a program using Qt library?

[kimu9]

Hi,

In the past, I used Qt to create some programs that were used within my organization. But now the organization is paid by an outside company to find/create a method/algorithm to solve their problem. Later, we have to implement the method into a program that will be used by the company. I am thinking about using Qt, but wondering about the license I need for this project.

I've read some discussion about the license and it seems that if an application uses only Qt's DLLs, it does not need a commercial license. Is that true? I wonder because my case is a little bit different from those discussed earlier, as the program will not be sold but used within the company to solve some particular problems. In fact, is this program that we will create considered a commercial software at all?

Also, according to the Qt's website, Qt has both GPL and LGPL...As I understand, GPL requires that source codes of the application that uses GPL protected library to be distributed while LGPL doesn't?? But then how can I know which license I shall need and how to choose it??

I am sorry if this kind of question has been answered somewhere. The legal terms in the license file just confuse me...also this program is probably one part of the entire project so if a commercial license is needed, it just might not be worth using it.

Thanks!