Hi @KouYuume
Thank you for reaching out to us, we are excited to hear your interest in the B2C Pro plan!
Allow me to try and clarify the questions that you have:
You are correct, under a B2C Pro plan you will not be automatically upgraded to an Enterprise plan. If your current subscription is B2C Pro with 1000 MAUs, and you exceeded the limit for three consecutive months, our system will perform an automatic upgrade so that your subscription fits your tenant’s usage. As an example, if you exceeded the MAUs quota of 2000 and your current limit is 1000, the system makes an upgrade to 2500 MAUs with the same B2C Pro plan, not the Enterprise Plans.
Auth0 does not impose hard limits on MAUs or M2M tokens for customers under a paid subscription. This way, we ensure that your service won’t be affected even if you exceed your limits. So, new users can still access your application and sign up.
Just to add, an email notification will be received by the tenant Admins once the quota limit is exceeded for the prior month, as mentioned in the following Knowledge Article: Auth0 Quota Exceeded
Hope this helped!
Gerald