As of writing, Subbly doesn’t offer pre-payment for your products. You can currently setup a product to be paid up front but as a subscription. E.g. 12 monthly shipments billed every year. This is the same except it renews at the end of the year.

However, please note that the "proper" pre-payment feature without auto renewal is on its way! In order for our developers to introduce this as soon as they can, please make sure to vote for this here.