Well, it looks like I made a mistake with the Dofus numbers.
What happened is that when Ankama talked about "Subscribers" in their press releases, they actually meant "Monthly active players". They did make a clear distinction between "Subscribers" and "Registered Users", that is how I made the mistake.
So while the 800k, 1,5m and now 3m numbers were not paying subscribers, they are Monthly Active Users, and still a nice number to have.
Their actual active paying subscriber number is 500k at the moment, still a very respectable number. Obviously this will be fixed in v2.1 of MMOData.net, and I will do my best to avoid flaws of this magnitude in the future.
Here are the links ( new one and the old ones ) :
Gamasutra Interview, 500k subscribers
Ankama press release 1,5m subscribers
Gamasutra interview, 800k subscribers