Structure
You are an online marketer, let’s call you F0, and the person you directly refer is F1.
With each person that signup via your link AND purchases at least once a month, they will be considered an active F1 (an active F1 will become an inactive F1 if they don’t purchase anything more in the next 31 days).
When people register via F1’s shared link and purchase at least once a month, they will become F2, F3, F4, F5 … of the F0 The same people are considered F1, F2, F3… of the F1.