ChargeBee Inc

ChargeBee handles the complexity of recurring billing, taxation, invoicing and automated email notifications required for renewals. 

Complex billing scenarios like proration, discounting using coupons, credits, grandfathering of price plans are all baked in as part of the product, so you can just plug & play to use the product. 

Provides a robust hosted payment pages option that can be customized to match your website, optimized for conversions. And there is also an iframe embed option for hosted pages that gives the best of both API and hosted payment pages approach. 

Here is additional reading material to glance through what ChargeBee offers to hep you decide and make the right choice.

https://www.chargebee.com/support.html