Hi llegrand,
Appreciate the response. Actually I am self-hosted, using Sentora. With Sentora I can make Hosting packages, there is also a PHP API. Currently I am looking at just linking across to the Sentora billing package from an Abantecart product - but it would be nice if it could be integrated better (and I think the Sentora API might let me do that), so I am reaching out to see if anyone has done that and is willing to share.