You can change your subscription anytime.
You will be charged the new rate on the next monthly billing cycle for your account.
Follow these steps to do so:
You need to go into your settings or App Store and choose subscriptions. There you need to select our app. You can now switch between monthly and yearly. Don't forget to confirm.
At this point Android doesn't allow to switch between monthly and annual and vice versa if you have an active subscription with us you need to cancel your subscription and once it is expired you can subscribe again with monthly or annual.