Membership Management Software with API to ClickBank ?

Hi,

I'm planing on launching a recurring payment product(downloadable software with license) on ClickBank.
Anyone knows of a good Membership Management software that works with ClickBank,
which automatically pauses subscription when payments stop ?
I need to be able to check from my server if the client is still subscribed to the service and allow access.
A few more nice to have features would be: coupons, special affiliate commission rate (for high performers).

I read about aMember and about DAP.
Anyone has experience with those or with other tools?
Do you know of any free tools ?
Does Clickbank have something like that ?

Thanks

Amember is popular .
no exp but i have seen it on other forums
I don't think there would be free tools in such genre .

DLGuard is good.