When the free plan is not enough, and you decide to upgrade to one of our paid plans, you can choose between monthly and annual billing periods.
The increased source key limit and all features are available immediately after purchase and are active as long as your subscription continues.
When you switch to a higher paid tier, you are billed proportionally less depending on the duration remaining in your current plan.
I.e., you upgrade from monthly Autopilot ($49/mo) to Enterprise ($199/mo) in the middle of the billing period. Your current plan is then canceled, and about $25 is deducted from the initial upgrade purchase.