I recently had a non-paying web hosting customer. 3 Months without payment for multiple sites. Finally after numerous warnings I replaced her sites with a 'this account has been suspended' notice.
That's not exactly a kill switch. If you're hosting the web site then of course you can deactivate it if they don't pay.
I think he was talking about delivering a finished software product to be run on their hardware, but that has a backdoor that allows you to access and deactivate it remotely.
I am curious how this would work legally. Once you have delivered the product, is killing it remotely equivalent to maliciously breaking in and destroying property?
Received payment that day.
Kill switches work wonders.