The Recurring Invoice functionality has been discontinued for new Partners. Please familiarize yourself with the enhanced Subscription Billing feature, which has been introduced as a replacement.
The Active toggle button allows you to change the state of an invoice between an active state and an inactive state.
The active state means the recurring invoice template will run on schedule and generate invoices to bill your customer. While the inactive state is a dormant or draft state. It will not generate any invoices and it will not bill your customer.
The default state for recurring invoice templates is the Active state, but you can change it anytime to suspend billing.