As of April 12th, you must go to Progress SupportLink to create new support cases or to access existing cases. Please, bookmark the SupportLink URL and use the new portal to contact the support team.
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Kinvey system doesn't give out any such warnings. But, you have access to active user dashboard in Kinvey Console which can give you information about daily/weekly/monthly active users.
FYI, any user of your app will not be denied service in any way. All the users will be able to use the system, even if the user count goes beyond 1000.