Reddit uses Adzerk API to improve native ad system
adzerk.com
adzerk.com
Edit: Well this is embarrassing, I was linked here through a user profile and didn't see that this thread was about reddit & adzerk.
Perhaps it's because when I signed up, ad serving was claimed to be free for up to 100 million impressions per month. That changed: http://adzerk.com/blog/2014/01/an-update-about-new-free-adze...
"Certainly! If you signed up for an account before January 6th 2014 and were actively serving ads, you can still serve as many impressions as you want for free up to 100 million impressions per month. However, to contact Adzerk support after your 30-day trial ends, you must purchase a support app in the Marketplace."
So I guess they disabled my account because I wasn't actively serving ads? It would have been nice if I had received some kind of notification at least.
There is no reason for him not to notify existing account holders. Heck, he could have done so after the decision was made, i.e. when it would have been too late for anyone to "game" his system. It's not that Adzerk doesn't continue emailing their "Zerkers" for other matters - in November I was notified of their "new homepage with new colors and logo."