According to one embodiment, a memory system manages wear of each of a plurality of blocks in a nonvolatile memory. The memory system receives, from a host, a write request including a parameter specifying a data retention term required for first data to be written. The memory system selects, from the blocks, a first block in which a data retention term estimated from the wear of the first block is longer than or equal to the specified data retention term. The memory system writes the first data to the first block.