How do you manage versioning in documentation for multiple service tiers?

Hello everyone,
I’m working on documentation for a project that offers two service tiers (basic & premium) with slightly different API behaviours. I’d love to get feedback on how other teams handle docs versioning in such cases.

Some of the questions I have:

Do you maintain separate doc versions for each tier, or branch a single doc with conditional content?

How often do you update the “basic” tier docs vs the “premium” tier docs?

What tools or workflows help you keep both tiers consistent without duplication errors?

Have you used any “feature‐flag” style documentation tools that display/hide sections based on tier?

When you make a change to core API behaviour, how do you ensure both tiers’ docs remain accurate?

Looking forward to hearing how you structure this in your team. Thanks!