Settings has a Devices screen listing everywhere you are signed in: a device summary, a coarse location, and when it was last active. The one you are holding carries a "This device" pill.
From there you can log out any single session, or log out all other devices in one tap. You stay signed in where you are, and we email you a confirmation.
Sessions last 30 days, and an account keeps at most 10 signed-in sessions; the oldest is signed out when a new one would exceed that. The list never shows raw IP addresses or technical browser strings.