I bought a license for iWork on eBay. My copy displays as "Volume License." Is this legal?"?

I am assuming the seller has a volume license and is selling serial numbers to strangers on eBay. Is there any legal issue with this practice, or is it legit? The entire procedure: I paid for a “download” of iWork in the ebay auction; seller instructed me to download trial of iWork and use the serial they provided; after entering serial, my copy of iWork now displays “volume license” in its About dialog.