This is a  Plus Add On.

Plus Add Ons are included in all Plus or higher premium membership plans.

There are a few scenarios possible with this Add On. Each scenario shares these common features:

• When users checkout for a main account (or are assigned one by and admin), a discount code is generated to allow sponsored members to sign up for the sponsored level for free.
• If a user has a discount code assigned to them, it will show up on their membership account and confirmation pages.
• Sponsored members will be linked to their sponsor through the pmpro_discount_codes_uses table.
• If a sponsor’s account is cancelled, all of their sponsored members will have their accounts disabled as well.
• If a sponsor’s account is reenabled at a later point, all of their sponsored members will have their accounts reenabled automatically.
• Sponsors (parents) cannot use their own code to checkout for membership.