Philip K. Dick, Ubik (1969):
Back in the kitchen he fished in his various pockets for a dime, and, with it, started up the coffeepot. Sniffing the — to him — very unusual smell, he again consulted his watch, saw that fifteen minutes had passed; he therefore vigorously strode to the apt door, turned the knob and pulled on the release bolt.
The door refused to open. It said, ‘Five cents, please.’
He searched his pockets. No more coins; nothing. ‘I’ll pay you tomorrow,’ he told the door. Again he tried the knob. Again it remained locked tight. ‘What I pay you ,’ he informed it, ‘is in the nature of a gratuity; I don’t have to pay you.’
‘I think otherwise,’ the door said. ‘Look in the purchase contract you signed when you bought this conapt.’
In his desk drawer he found the contract; since signing it he had…