Sometimes Stripe system declines credit cards when you try to pay for the service.
Kindly triple check that you’ve typed the correct information into all the fields. If yes, please check whether your credit card has sufficient funds on it.
If that doesn't help we suggest contacting your credit card issuer, it's quite common that the banks block the payments on their end.
For more info you can always hit us up on Intercom or at firstname.lastname@example.org.