Right...you have to get your coffee from your friends' machines. You can play a lot without real money. It does take a while for the energy to build up, but I just make sure to use it all say in the morning when it's full....then later in the day....then when I get home at night. So basically, take advantage of it every time it's full. To level up faster, when your energy is full be sure to spend some of it on evidence tiles. That makes your bonus bar go up, and then every time you find evidence or a collectable or whatever you get more XP for it.