alt Hacker NewsMy wife and I have occasionally made our own butter for years now... one thing people always forget to mention is that it goes bad really quickly. The trick is either to cut it up into chunks and freeze most of it and the remainder you keep in the fridge/defrost later will last about 3 days. Or you can add salt after you've done the separation but this does of course mean you now have salted butter... this will last up to two weeks usually.
Do you mold it with your hands under running water to wash away the remaining fluids? Doing that and salting it makes it last for many weeks for me. I don’t even know how long it actually lasts, I’ve always eaten it all before it’s gone bad. Making butter is a way of preserving milk, so it should last more than a couple of weeks.