As we previously mentioned via email when originally announced and in a second email in December, the $50 referral incentive was an end-of-year special promotion. It ended December 31st, 2019.
Please do not try to cheat the system: we are tracking if you are creating duplicate emails from the same ip address or are creating multiple accounts using the same shipping address. If you are caught doing this, you will force us to ban you from the referral program indefinitely.  A referral is an individual who 1) is not you and 2) does not live in your household.