The good news is that his mana stones can be converted into life essence by purchasing body parts with mana stones and refining those body parts into life essence.
The bad news is that he doesn't have an infinite amount of money. He hasn't made money for some time and will run out soon.
The last time he earned money was from the bet that he won after he survived the third mortal coil and advanced to the fourth mortal coil. He also earned some money by fulfilling the request of fighting the Daoist Pale Shadow of the Purple Flower sect.
Since then, he has had to forge many weapons and expand his dojo to every part of the Five Vein region. So he is running out of money.
He can still afford the expenses needed to get life essence now, but at the rate at which he is consuming life force, he will quickly run out of money. By his calculations, he expects to run out of money in a month.
