Chargebee allows you to create monthly paying subscription by configuring the Plan’s billing frequency as 1 month. If you want the subscription to last for 12 months and cancel at the end of it, you can set the No. of Billing Cycles field as 12.
If you want to restrict the customers from canceling their subscription from their Self-Service portal account, navigate to Settings > Configure Chargebee > Checkout & Self-Service Portal > Portal and disable the “Allow customers to cancel subscription” option.
At the end of the 12 months period, the subscription would automatically cancel. You can use the Extend Subscription option to allow customers to extend their subscription.
The option to restrict subscription cancellation only for a specific number of billing cycles is currently not supported. Instead, you can disable the option for customers to cancel their subscription and handle the cancellations on your end. In this case, you can leave the No. of Billing cycles field blank so that the subscriptions don’t cancel automatically.