However it seems that Samsung has decided that they will no longer be continuing it. In a notification sent to users, the company has announced that they will be ending the service come 10th of August, 2018. The message tells users that after that date, Samsung Rewards Points will no longer be available, and that users will still be able to use their unlocked backgrounds until then.
Samsung did not provide a reason why they would be ending the service, but presumably it is because it might not have been as well-received as they would have liked. It was designed to encourage users to keep using Bixby, so either it proved to be so effective that Samsung no longer has the need for it, or that it wasn’t effective that Samsung decided to scrap it instead of maintaining it. Either way if you have been taking advantage of it, come 10th of August you no longer will be able to.