With FTM 2010 (bought in the UK) I had to enter my credit card details in order to activate the free subscription - there was no code or voucher, you just selected the activate command from the help menu. The Plan view shows when the free 6 months are up, and I was able to cancel the subscription a few days before the end of the six month period - and my access actually continued until the very end of the six months. I was able to cancel on-line from my account - I didn't have to resort to telephoning. The only problem I encountered was trying to find out whether the renewal would be monthly or yearly - it appeared it would have been a six-month renewal but they didn't send me this information until after I had cancelled!
Anyway - they didn't take anything from my credit card.
Hope this helps