The validity period of the downline or friends that you invite using the referral ID on Indodax is 90 days. This period is calculated from the time the user verifies the account and makes a crypto transaction on the IDR market. After passing 90 days, the referral ID used is no longer valid for the downline. Where you no longer get rewards from the results of asset buying/selling transactions made by friends that you invite using your Indodax account referral ID.