Manage your subscription anytime from Dashboard → Profile → Subscription.
Upgrades take effect immediately; you get the new features, limits, and AI credit allowance right away.
Downgrades apply at the start of your next billing cycle; you keep your current subscription until then. When the new (lower) publish limit takes effect, Branvas automatically unpublishes products newest-first until you're within the limit.
Cancelling: you may cancel your membership subscription anytime. Your paid features stay active until the end of the current billing cycle; then your account moves to the Free plan. Once the subscription ends you can no longer fulfill orders through Branvas, and published products are unpublished (your selections stay saved, as in How does the 3-day free trial work, and what happens when it ends?).
Pausing: there is no separate pause option, and you don't need one. Cancelling saves all your settings and product selections, and you can resume your subscription anytime and pick up where you left off.
Uninstalling the Branvas Shopify app does not cancel billing. You must cancel the subscription itself, as above.