Adventure Time, Volume 7 (Adventure Time #30-34)

Finn is about to fall head-first into an adventure so intense, he'll never remember it! Finn tries to take on the Mnemonoid only to wake up in the future with no recollection what what has happened in the time jump! With his pals Jake, Princess Bubblegum, and Marceline, Finn must remember how to beat this mean dude before he forgets everything else!

Collects Adventure Time (2012) #30-34.