In general, Topps is a business and they want your money, but 2019 Topps Now Card of the Month is an example of being rewarded for money already spent (and, of course, the money you continue to spend).
Part of the Topps Now Loyalty program, frequent purchases at Topps' online store can add up to these exclusive COTM cards. This was also the case in 2018.
Each month, one 2019 Topps Now Card of the Month card is made available. Eligible collectors must redeem the card online using their coupon code during the allotted timeframe. After that, the cards are like the main 2019 Topps Now Baseball release in that they are retired and a final print run is announced.
2019 Topps Now Loyalty Program
The system works like most other reward programs wherein collectors earn points by making qualifying purchases. Points accumulate for 365 days and can be redeemed for discount coupons. For 2019, the rolling period is based on purchases made from May 1, 2018 to April 30, 2019. So, you may be an All-Star or Hall of Fame member and not even realize it. Complete details for the Now Loyalty program can be found at the Topps website.
Each collector that qualifies for the Hall of Fame tier, or invite-only Platinum, gets a 2019 Topps Now Card of the Month card every month. All-Star collectors can choose one COTM card during the season.
2019 Topps Now Card of the Month Checklist Gallery
April 2019 COTM - Cody Bellinger
May 2019 COTM - Austin Riley