A: For Tier 3, “fully available” means those features are available whether you use our default API access or your own key (BYOK).

So on Tier 3:

you are not restricted to BYOK-only for Brand Voice, Humanize Content, or AI Model Selection
you can use our supplied API access
or use your own supported key
or even mix both where needed

On limits/capacity, Tier 3 is the top tier, so it comes with the highest allowance, bandwidth, and flexibility under the current AppSumo offer. The normal creation limits of the tier still apply, but the features themselves are fully unlocked on Tier 3.