Anubhav It would only be used by someone you don't know, if you have shared, leaked or distributed your license key. If you have not done that, then of course nobody can guess your license key. If you believe you have mistakingly shared your license key, you should probably let me know. Or if you know a website that you suspect is using your license, you can report it.
We don't generally track "instances" per license as that would require storing every domain that is using the license. For customer privacy reasons, the information stored and checked on our side, is absolute minimal.
I can do manual checks. By reviewing authorization requests, if I suspect the license key has been shared, I can disable the license and contact the original owner.