It should be setup to activate when your paid plan becomes active. However, the API may not return the free lifetime plan as being subscribed so I'm not entirely sure even this will work. All the var2 statuses are as follows.
A = Active
R = Registered Unpaid
X = Expired
C = Unsubscribed
U = Upgraded to other
I = Invalid
So you may actually be able to use U (upgraded to other) and have the action target your free lifetime plan id.