Board Thread:Plants vs. Zombies 2: It's About Time/@comment-26368790-20150504084253/@comment-25982947-20150507030900

Reapeageddon wrote: People will waste the World Key for two worlds in that case, making it impossible to get LC. They could just beat the Gargantuar in both of the worlds they opened and get their 2 keys back.

Basically you can never lose a key, after unlocking a world you can always get the key back.