In short: cloud is metered by the hour and invoiced at the end of the month, and on the 15th as well until your account has paid two invoices. Your balance is no longer a brake for what is already running: your resources keep running after it reaches zero, and you are billed for what they used. Creating a new resource, or making one bigger, needs a balance that covers its first month until your account has paid two invoices; after that it does not. If you hold credit, the invoice is paid from it the moment it is issued, and all you receive is the payment receipt.
Everything else on RareCloud, VPS, web hosting, proxies and domains, is bought for a period and paid at order. None of this applies to them.
When the bill arrives
At the end of each month, for the cloud you used that month. Until your account has paid two invoices, a second invoice is issued on the 15th, for the usage so far that month. Anything under 5 EUR waits and joins your next bill.
If your account holds credit or bonus, the invoice is settled from it immediately. Credit that arrives later settles an outstanding invoice on its own, within the hour. Anything the credit does not cover is left for you to pay from your client area, with any payment method.
If a bill is not paid
The invoice is due on the day it is issued, because you have already had the service. You have 7 days to pay it.
Seven days later, at 09:00 in your own time zone, your cloud resources are powered off. They are stopped, not deleted, and nothing is lost. Paying brings them back, and while a bill is past due you cannot create new cloud resources.
If the invoice remains unpaid, the stopped resources are deleted, permanently, with everything on them. You receive a final notice at least 24 hours before. Like every other service here, a resource is billed while it exists, including while it is stopped, so delete what you no longer need.