If he stays chaste for a full month, then he can ask for me to unlock his cock for a little more fun.
After one month, he gets to cum ONCE. Usually he begs for me to suck his cock, or sometimes I just give him a hand job...
But, and this is the best part,... I always leave him begging for more.
Then I lock up his cock again, pet his balls with a naughty smile, and say:
"Be a good boy and you'll get an extra special treat next time!"