No, Affirm does not have prepayment penalties or fees for paying off your loan early.
Also, if you pay off your entire loan before the final due date, you will pay interest only for the period that you borrowed the money. Affirm rebates any unearned portion of the finance charge for the remaining loan period. To see the total pay-off amount, go to your Affirm account and click on "Make Payment."
Please note that Affirm financing is not currently available to Canadian customers.