Let's say you had a working Perpetual Motion Machine (PMM)[1].
What are you going to do with it? Work? Sorry, no. Work means overcoming resitance. If there was no resistance, you wouldn't call it work, and it would already be doing itself.
The moment you connect that PMM to the drivetrain of your car, or the main winch of that construction crane, or the electric motor at the heart of a power generator, you need to put more energy into the system. Once you give the PMM resistance to overcome, it stops being perpetual, and starts being just regular old-fashioned motion.
So: Not only are Perpetual Motion Machines impossible, but they're useless, too.
[1]I know, I know: It's not going to happen. But let's just say, okay?