We stayed at 5 different resorts on one trip this summer. We bought our mugs at the first resort, AKL (Kidani). When we were purchasing them I asked if we would be able to use them at the other resorts during our trip, and the CMs (two or three of them behind the counter) all said we would be able to use them.
At each of the following resorts, CBR, YC, BW, and ASMusic, we asked the CMs in the food courts and at the pools if we could use them since we purhcased them at AKL earlier in the trip. Each and every time we were told that we could use them. We had no issues, and were told things like "absolutely", "of course", " we would not expect guests to buy 4 or 5 sets of mugs on one trip". Of course we could have just not purchased them, but it really was a non issue for us this summer.