Hi,
I answer to your question
bq. 1. if i build mobile app for iOS/Android/Blackberry/other and my app is free download and the user need to pay for subscription/free. i need to compile it with QA dynamic libraries. right?
I don't know if mobile/embedded version follow the same licensing policies of Desktop version
bq. 2. if i change the current QT component code i need to set it as open source to keep the license agreement. right?
right
bq. 3. for testing, not distribution, i can use the static libraries.
yes
bq. 4. what is the different between commercial license and distribution license?
Some tool have license to develop and licence to distribute (run-time licence), Desktop version of Qt don't
bq. 5. how i get the commercial/distribution license?
Contact "Digia":http://qt.digia.com/
bq. 6. how much is cost commercial/distribution license?
There are many licence combination
single developer/single platform
single developer/multiple platform
....
Contact Digia