If you'd like to prevent your subscribers from cancelling too soon, you can use prepaid subscriptions or add a minimum order requirement in the subscription group settings.
Prepaid subscriptions
This subscription type allows your customers to prepay for a specific number of orders in advance. Setting your subscription to prepaid only ensures customers must pay upfront for a specific amount of orders to benefit from your subscription discounts. Read more about this in Prepaid Subscriptions.
Minimum order requirement
Minimum order requirements can be used with standard pay-as-you go subscriptions. This allows you to set the number of orders that must pass before your customer can cancel. You can read more about this in Subscription Group Settings.