1. A memory device comprising: a volatile memory; a first nonvolatile memory; a second nonvolatile memory configured to store management data indicating a relationship between an identifier of each of programs executed by a host system and address data of each of a plurality of regions of the volatile memory being used respectively by the programs; and a controller configured to save, in response to an event of power loss, data of the volatile memory to the first nonvolatile memory, wherein the controller is configured to: receive, after recovery of power, from the host system an identifier of a first program of the programs and address data indicating a first region of the volatile memory newly allocated to the first program by the host system; identify a region of the first nonvolatile memory where data of the region of the volatile memory being used by the first program before the power loss has been saved, based on the address data of the region of the volatile memory corresponding to a program having a same identifier as the identifier of the first program; and restore the data stored in the identified region of the first nonvolatile memory into the first region of the volatile memory.