When the mortgage becomes due, the borrower(s) will need to pay the amount borrowed plus interest charges, FHA Insurance and service fees. Payment can be made by selling the home, refinancing, or using other assets if available.
If you sell the home, any proceeds beyond what is due on the loan would belong to you. If the house is sold for less than what is due, the FHA makes up the difference to the lender. This is for HECM loans only, and only applies if the borrowers opt to sell the home.