PLEASE REMEMBER, This is only visual. It does NOT let you have items for 999 days. The item date will REVERT to it's original date after you restart S4.
Think of the fakeshop hack. That's what it is. Fake. It does NOT let you keep the items for a longer duration.
It works but it justs shows for example 2750 days but its the same as before for example before it was 7 days after that it shows 2750 but its still 7 days!!