Guild Wars 2

I was told,that this achivement atm isn’t infinite and you can get only 200ap from that achievement (100 complitions).But now Im over it and still getting ap.So the person who told me was wrong or I don’t understand something?

It is capped at 250 APs.

250 for Agent of Entropy, 200 for the Dungeon one

Wiki is your friend
http://wiki.guildwars2.com/wiki/Agent_of_Entropy
The Achievement goes on forever, however you get 2ap each time you salvage up to a max of 250.