Glad to report that I was able to cancel my subscription with a minimum of hassle from the online chat agent (he simply asked why, and I said I had no travel planned for the next month--a bit of a fib, but it worked). He did not invoke the 7-day advance cancellation policy. It remains to be seen if my account was actually canceled and I will not be charged for the next month (my Gogo account activity only shows a charge in September, not in October, so perhaps their systems are bit behind)...