Greetings!
First of all, I sell software also. Secondly, some unscrupulous eBayer reported me for selling 'Bootlegged' items on eBay a year or so ago.
eBay removed all of my listings, contacted all of my bidders/clients etc. informing them of this, and subsequently Suspended me for 7 days until I could, AND DID, provide absolute proof that, in fact, my items (all) were valid. This entailed me having to provide all of my Contacts, Suppliers etc. etc. as well as a letter from the manufacturers on-staff attourney contacting them to verify my distributorship status, As Well as private counsel and their fee's, As Well as larger manufacter(s) require a substantial fee up front as you probably already know, and having to maintain an annual quota on top of that to keep this complete distributer/ wholesale status.
After all wholesalers, distribtors, manufacturers were contacted and All receipts provided, my 7 day suspension that last several months of legal crap cost me several thousands of dollars, reputation, integrity etc. etc. etc. eBay was finally satisfied and re-instated all privilages in full, and I am also now selling the same software, or at least, similar.
Why did eBay take this action? Simple, just because someone, more than likely another seller in competition, reported, unfoundedly, that I was selling 'bootlegged, copy-rited software'.
I'm telling you this because you say "I know for a fact" yet you don't say why, or even how you know or came to this conclusion.
We all certainly understand why you don't divulge the identity of this seller, it would cause a defamation and other suits as well as legal and actions taken by eBay.
You might well have a very valid source of Proof, but again, all I know is like the eBayer that put me through all of this only provided the same comment(s) to eBay, "I know for a fact"...nothing else!
This is in no way meant to be an attack on you in any way and please don't presume it that way. I just want you to understand the consequences that people can have, and do/did before you act.
Reporting is very good advice, though before reporting to Trust & Safety or Legal Authorities, I would certainly contact the manufacturer(s) etc. first confirming that, in fact, this individual doesn't have the reseller rites to sell/auction these items.
There's currently 50 million+ sellers selling software on eBay alone! Certainly, out of that there is obviously a few that are indulging in 'illegal' activities, but I would Never report Anyone of them based just on assumption!
Also, you do seem very concerned about this issue. I'm very concerned about your motive. e.g. I've had other complaints from eBay in the past where I was offering a Free DVD Movie with a software purchase because another seller(s) felt that I was 'creating an unfair selling field' etc. etc.
I'm too busy with my own store to investigate every other sellers legitemacy, but then you don't need to prove that do you, only to make that drastic accusation(s).
Please understand that I would be the 1rst one to report anyone that "I knew for a fact" was selling illegal software or any other copy-rited items for all of that matter, But Only with very solid proof, in which case, manufacturer would certainly, and does, take these action(s) themselves.
Jeff