You have two options:
Option 1: Use the license key right away. Your bundle license activates immediately and overlaps with your store subscription. You may temporarily have two active Premium entitlements — but using a license key does NOT cancel your store billing. Cancel separately to avoid paying twice.
Option 2: Cancel your store subscription first. Cancel through the app store, and your Premium continues until the end of your billing period. On that last day — or whenever OBDAI drops back to Free — redeem your bundle license key. No overlap, no double-payment.
Most customers choose Option 2 to avoid overlap. Either way, your bundle license is yours to use whenever you’re ready.