Oapps for Viber costs $29 per Zendesk subdomain per month. You can add as many Viber channels as you want to one Zendesk domain without any additional fees. If you need more account, please reach our support.
The 14-day free trial will help you investigate all the advantages of the app from the inside. To use a free trial you should install Oapps for Viber from the Marketplace. When you install the application, you will still be asked to enter your card details - this is a Marketplace requirement, but no charges occur until the 14-day trial period ends.