For example, a $399.00 purchase might cost $35.08/mo over 12 months at 10% APR. Shop Pay Installments Monthly now also offers monthly installment options for up to 12 months*.The remaining three payments are deducted automatically every 2 weeks. Shop Pay Installments 4 Payment Option breaks your order total into 4 equal interest-free payments, the first due at checkout.Shop Pay Installments (powered by Affirm) offers a few different payment options, detailed below: RevAir offers payment plans that allow you to receive your RevAir just as though you paid in full today!