By default, you have committed to a one-year term, paid on a monthly basis. If you cancel your subscription before the anniversary is up, then you would be charged as an early termination penalty half of what number of unused months that you have remaining in that one-year term. This means that if you cancel after you have used only 15 days of the first month, you would be charged half of what you would have paid for the 11 months that remained in your subscription. Your cancellation would not become effective immediately upon the cancellation request, but instead at the end of the current subscription month. Because of that, the only way to circumvent the cancellation fee would have been to cancel within the very last month of your one-year subscription term, before you let the subscription automatically renew for the next one-year term.
You could have subscribed to a truly monthly plan - but that alone would have cost you 50 percent more money right off the bat for each and every month (compared to the default one-year paid monthly plan). And you must have selected the monthly plan manually when you signed up. If you didn't, then the default one-year-paid-monthly plan would apply.