It takes about 2 days For Provolone Cheese To Mold.
Frankly, I wouldn't buy as much so you wouldn't have to worry about it. I put my cheese into a freezer-type ziplock bag and force out as much air as possible. One way you could be getting your cheese a shorter life-span is cross contamination. Make sure nothing touches the cheese when using it. Clean, dry hands when you put it away. Don't let it sit out. Get what you need, and put it back in the refrigerator. If by some reason you think you have too much on hand, I would take a few slices, put them in a quart sized ziplock bag, put them in, get the air out, and freeze. They should last at least 3-6 months.