Activation & Deactivation Question

Hi one question

I've bought game by shop on official site, download and install with the key sent by mail, I've seen that there is 3 chance of activation for different pc, this is right.

But I don't understand why when I uninstall PCM2011 and deactivate it (only option avaiable) the counter of avaiable deactivation go down one, 5, 4, 3, and now 2...

There is a limitated numer of disinstallation possible? And what it happened when this counter down to 0?

Thanks