Gravis and his mother talked a long time about how to set up the shop, and eventually, they came to a consensus.
Gravis would give his mother 20% of all the earnings. In return, she would get the shop, handle all the bureaucracy, and be responsible for the security in his shop. The fact that she was handling the security was the most important thing. People that know that they will be tortured to death might become rowdy and attack Gravis. If his victim were an Ancestral God, Gravis would die.
With the help of his mother, Gravis didn't need to fear anyone inside his own shop. Only Peak Divine Gods could fight his mother, and Peak Divine Gods wouldn't enter the shop of a Star God torturer. They had access to the real torturers, which were basically all Divine Gods themselves.
It took the Economistress only a couple of years to set up the entire shop, and before he knew it, Gravis could already start working.