I have a shared album of which I am the owner and I have people that I shared the album with who "subscribe". Will I know or be able to tell if a person leaves the album/unsubscribes? Or will that person still be listed in the "People" tab of the shared album?
From what I can tell based on what I've read to this point, the person will not appear in the list of subscribed members. Whether or not you get notified if they opt to leave the shared album, I don't know.