You can unlock a trigger lock in more than one way.
One way is to use the key that came with the lock.
Another way is to use a paper clip or metal wire to push in the small hole on the back of the lock and turn it clockwise.
A third way, for locks with a number dial, is to turn the dial left until it clicks and then turn it right until it clicks again. The last number will be the one that is pushed in to unlock the trigger lock.