Go to Billing → Upgrade and choose a higher plan. You'll see a cost breakdown before confirming — SearchVitals charges only the difference in value between your old and new plan for the time remaining in your billing period, taking into account how much of your current plan's usage you've already consumed.
Upgrades take effect immediately once confirmed — there's no waiting for your next renewal.
If your subscription predates our current billing provider (a small number of long-time subscribers), in-app upgrades aren't available — contact support and we'll take care of it directly.