Card payments may fail for several reasons.
Temporary card failure
The card could not be charged due to a temporary error. We will try to charge the card again after a couple of days, to see if the error disappears.
If the card expires, then all subsequent payments will fail. In this case we recommend that you change your credit card details so your subscription can continue. You can see how you change your payment details here.
The company address has changed
If your company address changes then you sometimes need to update your credit card details accordingly. See here how to change the credit card details.
If the payment fails more than two times, your account will be immediately downgraded to the Free plan. Therefore, it's important to confirm your card information is up to date if you receive payment failure notification.
The card issuer is refusing the payment
If your transactions keep failing, it could be caused by your bank or card issuer blocking the transactions. This can happen for a few reasons:
The payment might have been blocked because it falls out of your normal shopping pattern
You're not allowed to make international transactions on the card
Specific rules apply to the card (a max amount in transactions, credit limits, or similar)
You should try contacting your bank, where they might be able to shed some light on the issues. Alternately, if possible, you could try with another card.