Here is the full list of all 15 AN IOU achievements.
Drink a Shirley Temple
Order Tequila
Complete Ending #2
Clean Blood
Paint at the studio
Take Mallory's Picture
Call Violet multiple times
Drink a Root Beer
Order an Irish Car Bomb
Tell Violet You Miss Her
Share Flask with Mallory
Complete Ending #1
Dine and Dash
Split the Check
Complete Ending #3