Using Adsense in place of a payment portal

I would like to modify the credit based payment system currently in use on an open source dating website that is used to purchase the site's features and updates. I would like users to earn the credits by viewing Adsense driven adverts instead of purchasing credits through one of a choice of payment portals. Furthermore, users should also have control over the frequency of these adverts - how often an advert is served in relation to each profile viewed - ranging from one advert for every 5 profiles viewed, up to one advert for every 25 profiles viewed. This will enable the users to determine how many credits they can earn. The reward structure ought to give users sufficient incentive and motivation while still ensuring that their experience on the website is not impacted in any negative way by intrusive or the overly frequent display of adverts. By having this balance of incentive versus access it will provide a user friendly atmosphere which keeps visitors happy and encourages engagement with the site.