From someone who knows how to use it. This should be you, but usually involves some training.
From me and the people I choose.
From Microsoft, Apple, Adobe, etc.
Oh, I'm sorry, Sir, go ahead, I didn't realize you were root.
From Dave.
I'm sorry, Dave. I'm afraid I can't do that.
What's that? Chicken?
Proprietary software means, fundamentally, that you don't control what it does; you can't study the source code, or change it.