Okey, if you are having issues with this Achievement, because it does not pop up do this:

1. Create a new game, do not use the master file, because that was my issue.

2. Reach level 15, is going to be easy, just go to the gym or library.

3. Now this is the fun part, before you buy the 3 books of the store, save your game, once is save, buy the 3 books, and finish the day, the game will auto save, after that, close the game and the achievement will pop.