After April 13, 2016, you will no longer be able to create a new iTunes Allowance. All existing allowances will cancel May 25, 2016.
After May 25, any unused allowance credit will remain in the recipient’s account until it's used.
Apple is suggesting that iTunes Allowance users use Family Sharing for managing purchases made by family members and iTunes Gifts for sending gifts to family and friends. Family Sharing has an Ask to Buy feature that will send you an alert when your child initiates a purchase, letting you review the item and approve or decline it.