When you purchase a membership, credits are added to your account every month. These credits accumulate monthly and do not expire as long as your subscription is active. If your subscription expires, you will lose your credits, unless you renew or switch to a different subscription (regardless of its value).

You can have multiple subscriptions at the same time. Each one grants access to all features; the only difference is the number of credits you receive each month.

Subscriptions with billing periods longer than a month (like yearly or quarterly) still provide monthly credits. The billing frequency only affects how you're charged, not your credit accumulation.