You earn 30% of every payment a workspace you referred makes during the 12 months after its first payment: the first subscription payment, every monthly renewal and charges for upgrading to a bigger plan.
Commissions are calculated on the amount actually paid. Free trial starts and workspaces that never pay earn nothing.
Good to know
The rate and duration are fixed when the workspace signs up. Later changes to the program do not affect referrals you already have.