After you have finalized the process to finance your flights with Affirm, you'll need to pay off your flight reservation price on the monthly payment plan that you agreed to. Affirm will send payment reminders by SMS texts to the mobile number that was registered to create your account. Make sure your phone number and email are up to date in your Affirm account so that you don't miss any travel payment plan reminders. Download the Affirm App as well to keep up to date with your payments. Your Affirm flight payments can be made online by debit card or ACH (Automated Clearing House) transfer on the Affirm website where you can also choose to set up an auto-payment. This can be before, during and after your vacation or travel.