Free Subscription + Keeping Track of Sub-Time

Hi,

I want to accomplish the following:

I have free online-courses on my website. I want my users (who may or may not already have an account) to be able to subscribe (for free) to one course with the click of a button.

Then I want to drip content to that user, so I would have to know when he subscribed to that particular course. I’d also like to sign him up to an e-mail list automatically (if he opts in by clicking a check box).

I’m guessing I’d accomplish part of it with custom capabilites and the content-dripping API. I just don’t know where to look for custom capability-subscription-date (not user registration date).

Anybody got any ideas? Is this possible with the pro forms?

Thanks for your help!

Macks