Even after the singularity the almighty AI has to work to pay rent...

Imagine the Earth is covered in a "Grey Goo" outbreak of spreading nanotechnology, infiltrating every corner of the planet in a constant churn of molecular and informational warfare. Eventually it leads to vast colonies of nanobots which rise thousands of units high clambering across the land, driven by vast inscrutable colony-minds.

I can tell you with 100% certainty that they will pay rent, because they are us.