Consumers are willing to pay monthly subscription fees for streaming services, pet food and even toilet paper. Large chains like Panera and P.F. Chang’s as well as neighborhood hangouts are increasingly experimenting with the subscription model as a way to ensure steady revenue and customer visits. “This is just another way for customers to provide a level of support and joy and love for our offerings,” said Matt Baker, the chef at Gravitas, a Michelin-starred restaurant in Washington.