Free - 30 Ultra Balls for Pokemon GO
Referee and referrer unlock various in-game rewards after referee completes certain tasks
Referee gets guaranteed 100 Pokeballs.
Should be 300 with how many I've gone through.
Actually providing a bit more information on how to redeem this would be nice; all there is to go on is squinting at a thumbnail of a screenshot of the game in a post on a non-english website that doesn't explain anything either.
According to this comment, in the shop at the top of the page.
So why not add that to the description instead of having people to dig about in comments or the like?
Thanks OP, now I can catch em all