They look at the their recent activity and how many pictures and videos they posted.
That may not seem like a lot, but they'll probably post more soon.
In my humble opinion, I'm not sure, I haven't seen enough data, yet.
Prepare yourself, I may disappoint you more, than my dad, when he went out to buy a pack cigs.
Doing so will result in legal action and termination of subscription without a refund.