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

The year is 1714, and a young woman named Addie makes a deal with a sinister god named Luc, who frees her from the confines of her hometown in France. Addie becomes immortal, but as with any trade with the devil, there are consequences. Although Addie can go anywhere she wants, she is unable to leave a trace of her existence, and no one will remember who she is, not even her family. Unable to put down roots or form lasting relationships, Addie is determined to live a fulfilling existence, especially when her soul is at stake. Three hundred years later, she is still alive and living in New York City, only still living as a mere shadow.