This sentence here "Promote legal use of medicines". Does anyone knows which word is the subject, predicate, and object? I really want to know so my mind can rest.
I don't know, no. But I'd guess "Promote" is the subject, & "medicines" is the object, implying "legal" to be the predicate.
It's an Imperative sentence, so the subject is the not mentioned 'you', Who is 'you' will depend upon the context. For ex, a public speaker might say "Please promote the use of medicines". So the subject is you, which in this case is the audience. Object is medicines And predicate can be the full sentence itself.
How does that "you" work if it's the mission statement of an NGO ('cos that's what it reads like on it's own)?
the same. In this case, the subject is also you. But 'you' now means whoever reads the message. Understand it like this, the NGO is basically saying "Hey you, promote the use of legal medicines" to whoever reads the message. It's the same case as in the commands a teacher gives in class. "Read the chapter" which means "You (a student), read the chapter."
No, "Mission statement" as in "Why we exist" (e.g. the answer when they have to register their purposes for charitable status, etcetera)... By definition that can't be an instruction to someone else.
It's the thing being described or talked about in that case. In your example, it's 'we'. Why is modifying exist. You can reverse the order of the sentence to get a clear picture. "We exist why." "How are you - you are how."
Promote - Verb; Predicate Medicine - Obj Legal - Subj Use - Verb; Predicate i'm conflicted about using Legal Use as Subj of break down it to 'legal' and 'use'