Soon Jarng - 2019-09-13

Hello,
As a hearing aid manufacturer, I want to commercialize the Dream AM / DRM Receiver code to replace my existing FM analog hearing aid.
After analyzing the Dream AM / DRM Receiver code, I found that there are a variety of external libraries, some of which are free software, and others that require a license fee.
So I'm trying to get a license agreement by contacting the vendors of the libraries that require a license.
Where can I get a commercial license for the Dream AM / DRM Receiver code?
I heard that Dream AM / DRM Receiver code belongs to GPLv2, but it seems to have a commercial license for commercialization.
If I can't have a commercial license because the Dream AM / DRM Receiver code is GPLv2, is all I do is just releasing only commercial program code that I have created by modifying the Dream AM / DRM Receiver code?
And when I release only commercial program code that I have created by modifying the Dream AM / DRM Receiver code, am I correct not to release other source codes that were provided by others (I believe I am correct not to release).
As a quick response of yours, we hope that new hearing aids for people with deep hearing loss will be released. Thank you.
Regards,
Soon