Yes, you can change your plan at any time. When downgrading, the change will take effect at the end of your current billing period. When upgrading, you will be asked to pay the prorated difference between each plan's cost, and will receive the difference in credits associated with each plan. For example, if upgrading from Starter to Creator, you would receive 5400-1000=4400 credits.

To avoid interruptions in service, you can enable pay-as-you-go billing in your account page. Pay-as-you-go billing will monitor any usage that exceeds your monthly allocation, and charge you at the end of the month - or when a preset threshold is reached - for any additional usage (see costs above). If you run out of credits and pay-as-you-go is disabled, you'll need to wait for your next renewal date or upgrade to a higher tier plan.

Yes, unused credits roll over indefinitely until you cancel your subscription. If you cancel your subscription, you will permanently lose any unused credits.

You can cancel your subscription by clicking the 'Cancel' button on your account page. If you cancel your subscription, you will permanently lose any unused credits.