Subscriber
Part of speech: noun
Definition: a person who subscribes to a publication or a service
Example sentence: Whether you're a Twitter follower, a YouTube subscriber or a Facebook friend, natural social instinct is to collect people and to not kind of see them later. But unfortunately, with social media, you collect them and they're in your life, whether you really want them or not.
Contributor
Part of speech: noun
Definition: A benefactor; someone who donates to charity or some cause.A person who backs, supports or champions a cause, activity or institution.A person instrumental in the creation or growth of something.A person who produces articles published in a newspaper, magazine, online publication, etc.