I freeze leftover coconut milk or buttermilk. It freezes fine and is a tiny bit watery when it thaws but no big deal. I use it a lot in marinades but never use the whole can. I pour it in a ziploc bag.
BTW, I had the Cowgirl cottage cheese this morning . I love the taste but not the texture enough to pay extra to buy it again. I prefer small curd and creamier.