If you have upgraded to Voxer Pro on web.voxer.com, you may switch between the monthly and yearly plans at any time.
To do so, login to web.voxer.com with your Voxer credentials and go to your Profile > select Manage Your Pro Subscription.
Cancel your current subscription, and start a new subscription on the correct plan. You will be refunded for any unused portion of your subscription.
If you have signed up for Voxer Pro via iTunes app store or Google Play store, you won't have the ability to switch plans mid-subscription.
In this case, make sure you cancel your subscription to avoid auto-renewal. Your subscription will be valid until the expiration date, and at the point you will be able to subscribe to the subscription of your choice (annual or monthly).
If you signed up for Voxer Pro within the app on an iPhone via the app store:
You can learn how to manage your iTunes Subscriptions and cancel Voxer Pro through this link:
If you signed up for Voxer Pro within the app on an Android via the play store:
You can learn how to manage your Google Play Subscriptions and cancel Voxer Pro through this link: