I was considering reducing the amount of commission from year 1 to year 2 to year 3 with no further commission for year 4 on the original subscriber. Example: John convinces subscriber a, b and c to join. Subscriber an and b are monthly subscribers, so John would receive a $6 commission from each of their subscription for each month that they maintain it. Subscriber c is an annual subscription, so John would receive a one time $60 commission. That would be year 1. If those same subscribers maintained their subscription in year two, the commissions would be reduced to $4 per monthly subscription and $40 per annual subscription. In year 3, the commissions would be reduced to $2 monthly and $20 for annual.

In addition, for each subscriber that a, b and c adds, John would receive a smaller commission that would also decline over 3 years.