Is there a way to tell if a 15+ ecu is properly unlocked for HP?

As the title says. Before I try to flash this thing, is there a way to tell if the ecu has been unlocked properly for HP tuners to be used? The truck has a supercharger installed and I've pulled the file from the truck. The owners claims its been tuned with HP in the passed but i'd like to know for safety sake before I attempt to change anything and either waste credits or brick an ecu.

Also, if the ecu has been flashed with HP previously and was unlocked, does that allow that ecu to be flashed by anyone with the software or is it a thing were its tied to the interface/dealer that had it unlocked?

Thanks guys.

If it allows you to flash it, it is unlocked. If it's not unlocked, it will give you a warning when you try to flash it.