I am always amused whenever I hear someone says something is a bit pricey, to which the philosophical answer is "Compared to…..".
Sometime, somewhere in the past, people got tired of moving 10 hens and 20 cows down to the village market only to then take them back home again if they couldn’t exchange them for something else they needed. So the coin was invented as a representation of the value of goods and an agreed exchange rate between people with different items and services. I guess sometime between that moment in time and the fall of Lehman Brothers, something went wrong with the idea, but the concept is actually still pretty valid.
Your boss wants to make sure that no-one modifies the developed, proven and tested software now that it finally works. If someone messes that up, perhaps there is damage to attached equipment, or maybe a software modification could affect production quality. Even worse still is if no one even realizes this has happened. There is a risk this could get expensive.
I suppose you will also be the person who then has to sort the mess out when someone else starts fiddling with the software. Unless you work for free, your time also has a cost and a value. Maybe the idea that someone doesn’t copy your program and sell it or just give it away to a competitor is also interesting.
Maybe that PAC Terminal Secure Strategy Distribution (SSD) software price-tag is not so pricey after all. After all, it does professionally resolve your problem for a fixed one off fee and it looks like it was designed and developed for necessities just like yours. Thinking over the above alternatives, maybe it’s actually too cheap.