In the US you don’t need a license to purchase a CNC. Even items with export restrictions like night vision goggles (Under ITAR) can be bought by anyone and shipped to your door. The export controls would only come into effect upon you exporting them.
All US firearms purchases made at gun stores involve background checks. In some states (like California) you are also required to do so for private party sales (like buying from your neighbor).
All states require you to get a background check on the purchase of a firearm from a gun store. Waiting periods are in a minority of states. Pretty much any felony, even nonviolent ones prohibits you from buying a gun.
The ‘gun show loophole’ is actually just the in private party sales (like selling your neighbor your gun) no background check is mandated. This is because the law requiring background checks is a federal law and the federal government has the authority to regulate interstate commerce but not intrastate commerce. Some states like NY have stricter background check laws than the federal law.
Bows, knives, & machetes all don’t require background checks. Grenades, technically any can get a license to own & make explosives but each one carries a $200 tax in addition to the hoops required to get the license, so pretty much no one really does that recreationally.
A lock does no more than keep honest men honest.
The truth is your security shouldn’t start and end with a lock. Locks deter non destructive low skill toolless entry.
Maybe you could rig something up with retractable badge holders. You might be able to get them for free from your work. 
Reach out to the seller. Assert to them that you own that IP and that it was released with a limited license that doesn’t include their sales. Say that they need to either stop or purchase a license from you to continue. If they don’t stop or want to get a license now is the point for you to contact an IP lawyer.
You could go straight to the lawyer option but this should save you some money and possibly resolve it without outside help.