The PGM2 system allowed for use of Memory Cards (supplied by the arcade, specific to each game / region) in order to save Character progress. Each card allows for a limited number of saves (500?) but allows you to store items, XP and money your character has acquired and reuse them between playthroughs. For the 0.193 release (or current GIT code) this is supported.
The English language version of Oriental Legend 2 does NOT have this feature (and the game is rebalanced to not require it) however the Chinese version does use it, so knowing how to use it in MAME makes sense.
Anyway, using it…
Once you get to the character select screen you’ll be presented with a 10 second timer to insert a memory card. It’s recommended you pause MAME at this point (with p)
It’s worth noting that without a memory card the bottom 2 characters are locked,you can’t move the cursor over them without inserting a memory card.