Three things. The third one is the one that actually matters.
One: keep the receipts, and keep them in your own name. Everything I have in my apartment today I have because a woman who was teased for fifty-one years about keeping receipts for bread kept receipts for a refrigerator. When an officer sat down at a kitchen table in Scottsdale with my blue folder, there was nothing to argue about. Not because I’d been clever — I wasn’t being clever, I was being the way I’ve been since 1973. But if you are buying things for a household that is not legally yours, put the purchase in your name, register the warranty in your name, and put the paper in one folder in one drawer. It is the difference between a sad story and a moving truck.