title: RxJS: BehaviorSubject unsubscribe
body: <p>I am very new to observables am worried about memory leaks.  If I create the following:</p>
  
  <pre><code>private client =  new BehaviorSubject("");
  clientStream$ = this.client.asObservable();
  </code></pre>
  
  <p>and susbscirbe to them in views like so:</p>
  
  <pre><code>this.clientService.clientStream$.subscribe(
    client =&gt; {
      this.client = client;
    }
  }
  </code></pre>
  
  <p><strong>do I need to unsubscribe?</strong> What if I called <code>client.getValue()</code>?</p>