Each of your monthly subscriptions comes with a specific amount of monthly credits. Each Image Generation Request (each request generates 4 different image variations) currently uses 0.5 credits (resulting in 0.125 credits per image).
You can always see your currently available credits by clicking the bell icon next to the logout button in the navigation bar.
You can choose between two options. You can either get another subscription including more monthly credits, or you can buy static credits for a fixed price. You find both possibilities in your profile section.
Brandity.ai subscribers can vote for future features. Each subscription comes with a specific number of votes that can be used to vote on specific features.