You have 40 people, you offer them one free 3day key to a friend (maybe 2). Now you've at most increased your possible player count by 200% which is a good max for early stress testing. Then once you find out it's stable at ~100 people you open a larger stress test. That's one of a few ways I can think of. @Xzoviac This game is still alpha so a small stress test like that makes perfect sense.
Basically you don't throw your game into the deep end as your first server stress test if you're new to server administration &/OR MMO creation. It's just asking to run into major issues. It would have been easier and less of a nightmare for them if they did a small test first. Otherwise you get frustrated people like me who honestly thought the game looked cool and the design was neat but can't trust that these people know what they're doing for me to give them my money at any point down the road.