know (one's) place
To be aware of the limit of one's role in a particular place or situation. I know my place, so I don't bother the CEO when I see him around the office. I'm just an intern, after all.
know one's place
to know the behavior appropriate to one's position or status in life. I know my place. I won't speak unless spoken to. People around here are expected to know their place. You have to follow all the rules.