Your subscription tier is based on the number of email addresses on your domain that have appeared in data breaches (excluding spam list breaches). If that number grows, for example, because a new breach is added to HIBP that includes addresses on your domain, your domain may exceed your current tier.
What happens during your subscription period:
Nothing changes immediately. If your domain grows beyond your tier mid-term, you can continue to search your domain as normal for the remainder of your subscription period. Your access is not restricted until renewal.
What happens at renewal:
At the end of your subscription term, you will need to upgrade to the appropriate tier for your domain's current size before you can continue searching. If you renew at your existing tier but your domain now exceeds it, search results will be limited to subscription-free breaches only.
What to do:
Keep an eye on your domain's breach count in the dashboard. It is worth checking this before your renewal date so you are not caught off guard. You can upgrade at any time by signing in to your dashboard at haveibeenpwned.com/Dashboard. Then navigate to Business > Subscription > Manage Subscription. Any unused credit from your current plan carries over automatically when you upgrade, as Stripe will pro-rata the amount.
Breach notifications will continue regardless of subscription tier. You will still be alerted when your domain appears in new breaches, even if a search upgrade is required.