ePay has a strange approach to handling subscriptions that is completely different from any of the many other payment gateways we have implemented in the past. Instead of scheduling the payments they simply give you permission to charge a credit card again in the future.
To me this seems totally backwards and also insecure from the point of view of the person paying (as once you get this permission you can charge any amount at any date in the future without the credit card owner giving you permission).
But the biggest impact of this approach from a development point of view is that you have to handle the scheduling of these payments yourself. We had to create a brand new and separate Joomla component to handle all of these subscriptions as RSMembership does not have this functionality. The component handles setup and scheduling of payments as well as handling what happens when a payment fails.
If you are in need of having a payment gateway developed for ePay to handle subscriptions or need to handle subscriptions using a similar payment gateway, then please get in touch. We have already done a lot of the hard work so we might be able to implement a solution for you relatively fast.
We also have ready to implement payment plugins for RS Membership and RS Events Pro for ePay.