learnrx | interactive exercises for learning RxJS | Reactive Programming library

I'm learning RxJS and am rather confused as to where the "listeners" are (in the Observable or the Observer), how they are subscribed/unsubscribed, and what happens when an Observer is "no longer interested in" an Observable, such as when you use take or takeUntil.

For the first part -- what's subscribed to what, what's a listener -- I'm confused by the seeming contradiction between these statements. From http://reactivex.io/rxjs/manual/overview.html we read that Observers are not 'listeners' to Observables

This is drastically different to event handler APIs like addEventListener / removeEventListener. With observable.subscribe, the given Observer is not registered as a listener in the Observable. The Observable does not even maintain a list of attached Observers.

but in http://reactivex.io/learnrx/ it says (Exercise 30) (highlighting mine) that

An Observable based on an Event will never complete on its own. The take() function creates a new sequence that completes after a discrete number of items arrive. This is important, because unlike an Event, when an Observable sequence completes it unsubscribes all of its listeners. That means that if we use take() to complete our Event sequence, we don't need to unsubscribe!

This seems contradictory to me. When you set up an Observable with, for example, fromEvent, where is the event listener? When you use take(1), for instance, on an Observable based on DOM events, what happens after the first event is sent to the observer? Does the Observer unsubscribe from the Observable, which continues to emit events, it's just that the Observer isn't listening to them anymore? Or does the Observable somehow unsubscribe the Observer, that is, the eventListener was in the Observable, not the Observer?

Thanks for any clues -- obviously I'm not seeing the forest for the trees, but the tutorials I'm working through, while they are good at trying to explain it conceptually, leave me confused as to what's actually going on.