So, why shouldn’t you sign up for yearly subscriptions? Many subscriptions offer discounts if you subscribe on a yearly basis, but a year is simply too long a time to accurately determine if you’re using the service and/or deriving real value from it.
I spoke about this on managing digital subscriptions on Mac Powers Users back in January. Rishabh makes a great point on yearly subscriptions. You'd be a lot better off to do the monthly option for a few months to make sure that you will want it for a year.
You might also choose to sign up for a service intermittently. For instance, I have a Netflix account that I only pay for occasionally when I know that I’ll make time for watching films in a given month. It also makes watching TV more active versus watching it passively, and the same goes for magazines, online subscriptions, online services, etc.
Another great point.