Here is a response that I got after a week and a half of following Parallels's instructions for setting up Plesk Billing. Mind you I had a fully functional bundled v5.6 plesk billing module. I could run it either via the bundled interface or standalone. I didn't necessarily see the need for the bundled version, and used the standalone version (I am a Perpetual 250 license holder). I then upgraded my CP to 9.0 and was looking forward to using the now allegedly improved and tightly integrated Plesk Billing 6.0. Well the upshot of the whole situation is explained pretty clearly I guess in this response from technical support: So apparently, Parallels is really offering 2 separate packages. If you own a ModernBill or PleskBilling license you can only use the standalone version. If you then want to run the "bundled" version you need to BUY an additional license beyond what you already have..... this is simply stupid and REALLY BAD BUSINESS!