The current membership feels pretty worthless right now, Here are some things that will make people consider getting a MS more.
-Add a NPC only for members to Excavation sites that allow you to teleport teleport through excavations sites for a small fee. You can even add a discovery requierement for it too.
-Change Bosses Pve coins reward maybe 8 on hard and 5 on medium for members from the original 5/3 rewards.
-More Safari time for members just a small increase would be good.
-Increase bosses limit to 25 instead of 20.
-Add more exclusive content for members overall, We have 5 member only areas and only one its worth going because theres a boss in there.
Any of these changes will make MS feel a little more worth getting for players and won't make a huge impact on the non MS player base.