The Invisible Life of Addie LaRue by V. E. Schwab

When Addie LaRue makes a pact with the devil, she trades her soul for immortality. But there's always a price -- the devil takes away her place in the world, cursing her to be forgotten by everyone. Addie flees her tiny hometown in 18th Century France, beginning a journey that takes her across the world, learning to live a life where no one remembers her and everything she owns is lost and broken. Existing only as a muse for artists throughout history, she learns to fall in love anew every single day. Her only companion on this journey is her dark devil with hypnotic green eyes, who visits her each year on the anniversary of their deal. Alone in the world, Addie has no choice but to confront him, to understand him, maybe to beat him. Until one day, in a second hand bookshop in Manhattan, Addie meets someone who remembers her. Suddenly thrust back into a real, normal life, Addie realises she can't escape her fate forever. 'For someone damned to be forgettable, Addie LaRue is a most delightfully unforgettable character, and her story is the most joyous evocation of unlikely immortality.' -- Neil Gaiman