Whatever man can create, man can destroy - including this kind of copy protection. You are not going to be completely successful in such a scheme because Access cannot hide its data completely. Someone with skills at a par with your own - or someone who reads this public forum - will be able to defeat your scheme, particularly since it is table-dependent. For example, what if they just rename the darned file and run it under a name that doesn't match the company's actual name. So to use your example, what if MarsCo decides to use this app and name the file HersheyIntl?
EDIT: I see theDBguy recognized the same flaw. But I had a longer message following it.
You MIGHT be able to get away with some sort of code-based scheme where you create a hard-coded item in VBA that uses an encryption scheme to hash-encode the name you are looking for but usually the trick will be some sort of two-stage approach. You CAN write a registry key and if you make it a hashed key based on, say, the computer's hardware serial number or some other such item, you can lock it down to that machine. There are other schemes. You would have to search this forum for "licensing a database" because this isn't the first time someone has asked such a question.
I think invariably, your issue is that you can't trust your customers. But what you might do is perhaps hide some CDO code somewhere that if your software is used on a new machine based on this being the first time you see a given serial number, send a message to yourself. (Of course, that requires that the internet be up, but you can make that a requirement, and you can refuse to run if the CDO .Send operation fails.) Then confront the person to whom you gave that copy. And the code could identify itself as well based on contract numbers or such. You could not stop this bootleg use - but you could at least know about it and initiate legal action.
