Some of our legacy free plans have recently received the message that they may be monitoring too many websites, when this may not be the case. These accounts were built before CopperEgg introduced custom metrics. These accounts do not support custom metrics and will show the error if custom metrics are enabled.
To resolve the situation, there are 2 options:
1. Move to a Starter plan, where you get all that is included here: http://copperegg.com/copperegg-pricing/. You can upgrade to the Plan in the Settings Tab > Subscription Settings
2. Remove and delete your custom metrics. Custom Tab > Metric Groups