Suqah leather is obtained by tanning suqah hide at Rimae Sirsalis for 100 coins per hide. These hides, when used with a thread and needle, can be used to create lunar torsos, lunar legs, lunar boots, and lunar gloves.
After one has finished the Lunar Diplomacy quest, they cannot craft lunar equipment from suqah leather. If one loses some of their lunar equipment, one can only recover them from the Oneiromancer or Perdu. This item therefore becomes useless after the quest.