I have been curing olives for some time now using the lye method, anyway I make a brine using 1 cup plain salt to 1 gallon of water, the olives will keep for months. These olives are a bit salty but not to the point of needing to soak them before eating, of course you could. I seasoned the olives with fresh garlic and red pepper flakes, very good.
To prevent the mold issue why not replace the brine with your own solution? The last batch I made has been in the refrigerator since November and no problems with mold.
Tim