Metalloendoprotease which is required in the dorsal paired medial neurons for the proper formation of long-term (LTM) and middle-term memories (MTM). Also required in the mushroom body neurons where it functions redundantly with neprilysins Nep2 and Nep4 in normal LTM formation. Preferential cleavage of polypeptides between hydrophobic residues, particularly with Phe or Tyr at P1'. Binds 1 zinc ion per subunit. In embryos, expressed in the central nervous system from stages 14 to 17. In third-instar larvae, expressed in the brain, ventral ganglion and midgut. RNAi-mediated knockdown in the dorsal paired medial neurons impairs middle-term (MTM) and long-term memory (LTM), but has no effect on normal aversion learning and anesthesia-resistant memory (ARM) (PubMed:27629706). RNAi-mediated knockdown in all mushroom body neurons has no effect on learning, ARM and LTM (PubMed:27629706). However, simultaneous knockdown with Nep2 or Nep4 does impair LTM, and simultaneous knockdown with both Nep2 and Nep4 results in a further reduction in LTM formation (PubMed:27629706). Wild-type females mated to males that undergo RNAi-mediated knockdown, lay the same number of eggs and have a similar hatch rate to those mated to wild-type males (PubMed:24395329). Belongs to the peptidase M13 family.