A licensee may, if the agreement governing a revolving credit plan so provides, impose different terms (including, without limitation, the terms governing the periodic percentage rate or rates used to calculate interest, the method of computing the outstanding unpaid indebtedness to which such rate or rates are applied, the amounts of other charges and the applicable installment repayment schedule) in respect to indebtedness arising out of purchases and indebtedness arising out of loans made under the plan.