I'd recommend you check out Recurly. They are one of the leading solutions in the recurring billing space, but also support one-off orders. Recurly answers most common e-commerce use cases, will also give, out of the box, rich plan/subscription management functionalities to all the teams within your organization. They also come with great documentation, and SDKs, which from an Engineering standpoint, made it a very enjoyable pilot to work on, at the time. You'll also get great visibility/BI/analytics for free, allowing you to monitor the health of your business. Your Finance team will also get all of the data that they want. Without having you write any line of code. As you did touch upon integrations, they integrate with major payment gateways, including their own, support webhooks, integrate with Segment and therefore any tool that integrates with Segment, which makes this solution one of the most extensible one you'll find. Eg. Triggerring some Email Marketing "journey" (workflow) in AutoPilotHQ based on certain events.