In June of 2015, the FAA announced that it will remove support for World Aeronautical Charts (WACs). You can view the official notice here. The FAA plans to introduce new VFR charts to cover the Caribbean before the WACs that cover that area are discontinued. Below is a table showing the expiration date for every WAC.
Image 1: WAC Expiration Schedule.
If you download a WAC before the expiration date, the charts will remain accessible, but a red “Expired” banner will show in the Maps view when those charts are viewed. At that point they can be removed from ForeFlight by tapping MORE > DOWNLOADS > DELETE > DELETE EXPIRED.