Can I change my billing cycle?
When you have bought a website or service:
Get in contact with your account manager and there will probably be no problem with changing the billing cycle.
When you have bought an extension:
You basically bought a subscription. This subscription is paid upon purchase so there is no billing cycle to speak of. When your subscription nearly ends you will receive a reminder to extend the subscription for the length of that subscription.
KB Article: https://loginsecure.eu/helpdesk/knowledgebase/view-article/25-can-i-change-my-billing-cycle