The "terms" list only valid is code used at time of order, and only valid on orders placed after March 21, 2019. Here is the exact language ...
"Related vehicle order must be placed after March 21, 2019. Referred vehicle orders must be delivered to qualify for awards. Model Y and used vehicle orders are not eligible. New or leased Model S, Model X and Model 3 orders are eligible. Referral code must be applied at the time of order and cannot be added after the order has been placed. Founders Series Model Y drawings happen on a monthly basis with the first drawing occurring on/around May 1, 2019. Founders Series Roadster drawings occur on a quarterly basis with the first drawing occurring on/around June 30, 2019. Credits awarded for qualifying referrals are valid for 12 months from the credit award date and can be used toward services, vehicle accessories or new Tesla products. Referral credits cannot be applied against solar lease or power purchase agreement payments. Free Supercharging miles will apply to any vehicles on the same account, and expire 3 years after the most recent miles are added."
But I think there is a typo in the terms, I think the "... and can be used toward services, vehicle accessories or new Tesla products" is supposed to state "cannot be used toward services ..."