Hi @NickHNZ and welcome to the Community!

Since Klaviyo operates on a subscription model, if payment fails, it will be retried a couple times until it succeeds. If there is an issue with your card or there aren’t sufficient funds available in your account at the specific payment date, your account will be suspended until the payment is completed. 

If you need to pay it immediately, you will have to reach out to our support team

I hope this helps, and thanks for using the Community!

- Brian