My software interacts with other commercial software in a very loose way. It just calls the other software passing some arguments. The first thing you see appearing when that opens up is who it's licensed to. I've seen the same licensee's name appear numerous times. As I said I work in a niche and these guys have WhatsApp groups and the like and pass stuff around. A group of them formed a brand, just a common website really, and then tried to beat me down on support costs despite the fact that forming this group had zero effect on my workload,same number of shops, same separate workforces. They don't always activate Windows, I doubt if their MS Office is always legal, they skimp on general tech support and try to get me to do that for free cos if their network is down my software doesn't work properly so it's my problem. One of them who's still my customer did try and pirate my software in a new shop and it was a few months before he had to come clean because it was obvious that support calls were coming from two locations over a hundred miles apart which had the same licence. If these guys had the source code the first thing they'd do is hire someone in India and see if he could replace me.