In Where's My Water 2, I've made it to level 30 but there is a locked barrier requiring 3 keys to proceed.
I can supposedly request keys from friends but when I went back and completed the first level it said I was the first of my friends to complete the level, so I'm guessing none of my friends have the game. (Regardless, it doesn't look like the game tells you which friends are playing anyway - I don't want to spam my friends who don't have an iPhone, let alone the game.)
As far as I can tell the only other method to progress is to buy a "Keychain". But it's not clear what exactly I get for my purchase. Do I only get the 3 keys for that lock? How much further in the game does that get me, and are there other locks I would need to pay for later?