A thing that I don't leave my house without

When I go out from my house, I have important to things to bring with me. It depends of what kind of place I go.  But there is a thing that I always keep with me when I go out, this things are my keys. I have three copy of each key from my house. I consider my keys that are my important things because I remember a day when my parents traveled for a week and my uncle had to take care of me. But this day I went to play soccer at the park. And when I went to my house I notice that I lost my keys. I didn't decide to return to find it. For that decision I couldn't went out again because in the afternoon my uncle always went out to buy his newspaper. And he asked for the keys because He knew that I played soccer every day in the afternoon and he delayed almost an hour. But I didn't have the keys so I answered that I didn't went out because my friends were punished. So You shouldn't leave your house without your keys.