A users subscription is stored in _cbsubs_subscriptions. Not sure which column you'd use for that as everything is calculated. My guess is if last_renewed_date is 0000-00-00 00:00:00.

What does the "status" column mean, and can we use that to filter "trial" members?

It's the current status of their subscription and no.

We have noticed the status show : A, C, R or X

A = Active
R = Registered Unpaid
X = Expired
C = Unsubscribed
U = Upgraded to other
I = Invalid

Ideally if the user is on a free trial it's the first time purchase of the plan so you'll want to first check that the "status" is "A" (Active) then check if "last_renewed_date" is equal to the date they subscribed (e.g. `subscription_date` = `last_renewed_date`). That would give you those who have subscribed once, but not yet renewed.