Currently, we don't offer prorated billing when upgrading plans. When you upgrade, your billing cycle will reset immediately, and you'll be charged the full amount for the new plan. However, you'll receive some benefits with this approach:1. Your new credit allotment will be added on top of your existing credit balance immediately
2. Your billing cycle will reset, giving you a fresh month to use your combined creditsWe are working on implementing prorated plans and credits for future upgrades, and we'll announce when this feature becomes available.
Sources:How can I change my plan? - FAQ | Clay.comCredit Rollover After Upgrading Plan