best way free observer handler

[icoco]

const sub = new Subject();

sub.subscribe({
next:(r)=>{
...
},
error:(e)=>{
..
}
})

...
question is if need call unsubscribe() manually ??

I track my code that do subscribe handler, seem it was hold forever, I meaning seem not been free .

little confuse, or give some online official link on this type issue , thanks