Actually, the question should be "why do other dairy products spoil so fast?"
If I remember correctly, the spoilage of milk is caused primarily by lactose, which breaks down into lactic acid over time due to the presence of Lactobacillus bacteria, which thrive in that environment.
Butter is mostly fat, and fat does not go bad (it does eventually, but not in the same way or at the same rate - see below) - lactose and sugars together, on the other hand, go bad quite fast. That is also why cream lasts longer than whole milk, and whole milk lasts longer than skim milk. It is also the reason why lactose-free milk seems to last forever - there's nothing to break down, nothing for the bacteria to feed on.
When butter does go bad, it's generally not even for the same reason - it's simply due to oxidation which causes rancidity, similar to a typical vegetable oil.
In short, butter lasts so long with or without refrigeration because proportionally speaking, it doesn't have as much of the lactose that causes other dairy products to go bad.
Still tasty gives you 2-3 months on cheesecake in the freezer. It will be safe indefinitely at freezing temp, but the texture will change somewhat. As @ElendilTheTall says, foil and plastic wrap are your best bets. Additionally, I might try freezing it for a day to get solid, and then sticking it in a vacuum sealed bag. If your seals aren't airtight on something else, then cheesecake will pick up any funky odors in your freezers.
Congrats btw, and I'm gonna let you in on a secret about the eating the wedding cake at 1 year - it all tastes worse and some tastes really bad. Normal or cheesecake or whatever, the cake is pretty much always bad by then, but luckily it's not about the cake taste. It's about reliving the memories and laughing over bad cake. So don't worry too much about if the cake is not that tasty then - take a bite,remember the wedding, and have a good chuckle.
Best Answer
If you are asking about butter creamed with sugar, you can do this. I would place in an airtight container, maybe with a piece of plastic or wax paper on top, and refrigerate. It should be good for a couple of weeks. Of course, you will need to bring to room temperature to soften before use.