Yes, we have developed a Capture Amount API, which allows you to capture reservations that are made using the SDK. An AppSwitch reservation will expire after 7 days, if it doesn't get handled. Handling is done by the merchant by either withdrawing the money and thus completing the purchase or by cancelling the reservation.
The reservation itself should in principle be canceled when the merchant knows that they will never complete the purchase / withdrawal. It is therefore the merchants responsibility to delete reservations. A nice solution would be to implement a cleanup job that continuously looks at active reservations on Merchant AppSwitch Agreement and delete the relevant reservations.