Upgrades
Upgrades take effect immediately. We prorate the difference between your old and new plan for the rest of the billing period and charge it on the next invoice. New seats/accounts become usable as soon as the upgrade is confirmed.
Downgrades
Downgrades take effect at the next renewal — no proration credits. Until then, you keep your current allowance. This lets you finish an in-flight audit on the plan you started.