My brother belongs. You have to make sure that you always have at least 1 CD in you queue because they charge you the $6.99 on the day of the month that you registered whether a CD is shipped or not - and once that date has passed, they will not ship you another CD for that month.
This is their comment on the resale (right from their terms & conditions page): "7.CDs Are For Personal Use Only: All selections purchased through yourmusic.com subscriptions are intended for personal use only and not for resale or any other commercial purpose. If we determine product is being used other than for personal use, we will cancel your subscription. "
You are also limited to a maximum of 2 copies of one CD.
You can cancel at any time - it's not like the Columbia House or BMG (even though it IS BMG) where you are required to buy so many CDs before you can quit.