After canceling, all team admins will receive an email notifying them that the subscription is about to expire. Unless you reactivate the subscription, they will no longer be able to change the team size or subscrition plan.
Once the subscription expires, all whiteboards within your Boardmix team will be locked in read-only mode for all team members, and you will be downgraded to the free plan. The whiteboard files will not be deleted.
The cancelation takes effect after your current billing period. Until then, you have access to paid features.