A license is attached to a specific V2; so if you flash your truck with your V2, and then try to modify the tune with your buddies V2 you will be required to license the ECM to that second V2.
A file can be saved independently to flashing. ie. you could write 20 different tunes and save them and not use a license until you flash them. Those 20 tunes may be for the same truck or multiple trucks. VIN # in the tune is irrelevant, our licensing is based off ECM serial number.
You or a tuner can write a tune, save it and email it off, and when the end user flashes it into their truck it will be licensed with that V2. This feature is not only valuable for professional tuners, it's also valuable for the whole tuning community and file sharing via email and/or the tune library.
The general scenario for Duramax is....Someone uploads a tune in the tune library, you download it, you read the blurb on the tune, look at the change made and then make a decision about running that tune in your truck (or applying the tuning principles used on your own tune)
There is another point here that needs to be considered, for those people who run multiple ECM's in the one vehicle ie. a stock ECM and a modified ECM), if you decide to flash both, you will need to license both given the serial numbers are different.
Cheers
Cindy