CBSubs fallback subscription

I would like a user to be automatically subscribed to a CBSubs subscription when their current subscription expires.

Case in point I have a paid subscription that when it expires I'd like it to fall back to a free lifetime subscription until they decide to upgrade back to a paid subscription.

How to I configure the fallback subscription plan when a paid subscription plan expires?

You'll need to use CB Auto Actions and its CB Paid Subscriptions action with the below.

Plan Active
Global
Triggers: onCPayUserStateChange
User: Automatic
Access: Everybody
Conditions
1: [var3] Equal To PLAN_ID_HERE
2: [var2] Equal To A

Plan Expired
Global
Triggers: onCPayUserStateChange
User: Automatic
Access: Everybody
Conditions
1: [var3] Equal To PLAN_ID_HERE
2: [var2] Not Equal To A

You can then subscribe them to another plan on plan activation or expiration as needed. Your alternative is to make the paid plan a child plan of the free lifetime plan, which will require them to always have the parent plan.