A free-market solution to preventing further domestic abuse

This society has gone full-on free-market everything including the punishment of severe domestic abuse. As a check on the abuser, the abused is granted a perpetual (or very long, 20 years or so) murder-right on the abuser, and only the abuser. This murder-right is the right but not the obligation to kill the abuser at any time.

We note that the abused are frequently strongly averse to violence themselves (or they might have resorted to it earlier in their own self-defense). For this reason, the murder-right can be transferred to a third party with the stipulation that the right can only be exercised when the restraining order is broken. The murder-right and accompanying restraining order are granted by the court after the abuser is convicted of serious domestic abuse. Should the abuser restrain themselves, they have nothing to fear.

So we have an NGO that buys murder-right contracts from the abused then exercises them when needed. However, killing people is expensive. One has to keep track of them, weapons need replacing, ammo isn't cheap, legal retainer fees add up quickly...and good sociopaths are hard to come by. This NGO needs to make money and lots of it.

What is a viable, long term business model for this NGO and how do they make a profit? The NGO must pay the abused for their murder-right in a one-time payment. It should also be resistant to bribery by a very rich-abuser (though getting paid twice is always preferable).

Out of scope

• This NGO only deals with serious, long term domestic abuse. Peeping toms and other lesser offenses are just out of scope. Murder of the abused is also out of scope.
• This question does not deal with defining processes for determining if a restraining order has been violated. A magic oracle determines if the order has been violated or not.
• This question does not deal with determining exact definitions or gradations or styles of domestic abuse. This question only cares about 'serious domestic abuse'
• How the abuser is killed is out of scope unless the method for death somehow makes money for the NGO.
• How an abuser might protect themselves from this NGO unless those protection measures are means of income for the NGO.
• While it's likely that there would be more than one NGO, this question only addresses the business model of a single NGO. Describing market dynamics between multiple NGOs is a separate question altogether.
• Proposal for a different market system for dealing with market abuse is also out of scope.

Note to downvoters, if you would be so good as to explain why you're downvoting, that'd be really helpful, thank you.

Further Reading:

• PRIVATE CREATION AND ENFORCEMENT OF LAW: A HISTORICAL CASE - A description of a heavily market driven approach to the punishment of murder.