People don't want to subscribe to stuff. They only do it when there is no other choice. If your site only offers subscriptions, I'll make a site with a one-time payment thing, store the users payment information and sell them new 'innovations' and 'features' that will be as easy as clicking a button to get, and that will bring me more money that your subscriptions.<p>If I have someone using my site all the time, it's easy to sell him something new.