Whether you're wanting to upgrade or downgrade your subscription, as long as you're the owner of your account you can change your subscription at any time.
1. Log into your account.
2. Click on the user dropdown in the top right hand corner of your screen and then click on 'Account settings'.
3. Go to the 'Upgrade' tab and choose the subscription you would like. You can use the frequency switch on the top-right corner to toggle between annual and monthly subscription options.
4. Select either 'charge to existing credit card' or 'enter new credit card details'.
5. Click on 'Pay Now' and you're all set!