My Remaining Lifespan Is Dangerously Low

In the Age of Declining Dharma, the cultivation world has modernized. To live longer, people have made lifespan the universal currency:

In this world, a steamed bun costs the lifespan of one incense stick, about five minutes by today's measure. A meat bun costs the lifespan of one cup of tea, about ten minutes. A dish of peanuts and a pot of rice wine cost a quarter of an hour of lifespan, about fifteen minutes.

As for the protagonist... his lifespan balance is dangerously low...