Subway Surfers is a popular game where players run endlessly across train tracks to achieve high scores and unlock more and more characters and abilities. You must earn keys as you play to unlock new characters or board "skins" (some of which affect gameplay) and to keep playing (rather than starting over) if you fail.

Keys (and tokens) can be purchased directly in the game in various amounts, but you can also earn them for free by playing the game. There are five different ways to earn keys in Subway Surfers without paying real money:

As you run through a given level, you’ll see all sorts of floating items that you can pick up, always including precious keys. Getting them this way is fairly easy, but can also be tricky.

Be patient, but keep playing, because you probably won't see them very often.