This might not be the right thread to ask... I'm soon going to put up my android app. Is there such a feature on the android market where I can offer promo code

This might not be the right thread to ask... I'm soon going to put up my android app. Is there such a feature on the android market where I can offer promo codes to users like apple's app store? Or do I have to bake in such a feature into the app on my own?