All paid subscribers have access to a Pokémon Go Friend directory as a way to add fellow One More Catch readers as in-game friends.
This is useful for sending and receiving gifts (great for XP and pinning postcards for Scatterbug regions) and, at the highest friendship level, performing Remote Trades. It's also possible to jump into raids remotely through invites or by joining directly from your friends list.
In other words, if you're in need of a friends boost with a small, select group - including the One More Catch editor - this will come in handy.
I should add this is an optional feature. There's no obligation to take part, add other subscribers, or keep on top of gift-sending if you do join - but if you're interested in taking part, the submission form and directory of users is below.