In an Apple Upgrade lease, your monthly payments cover only part of the device's value — the portion that depreciates over the lease term. This final payment is called the Purchase Option Fee, which is the device's remaining residual value in case you don't upgrade or return the device at the end of the lease. This structure keeps monthly payments lower, but means a larger amount is due at the end if you want to own the device outright. The exact Purchase Option Fee amount is shown in your lease agreement before you sign.