[martswite]

I've never understood why any service should need my card details if I'm signing up for a free trial. I now don't sign up to free trials that require payment details up front because, often, there isn't any warning before the trial period ends and a large charge can then get taken.

If I like your service and it's useful to me after the free trial ends I'll sign up and add my payment details.

I'm probably just cynical before my time but I see it as preying on people who are forgetful, to take their money.

In answer to your question though. I'd send a reminder it's polite.