It’s probably because you use some feature which is out of the range of your license edition you use. Please check feature matrix. You can see which module is being used on your site and it is not listed for your license edition. Also, if you go to event log: 'Site Manager -> Administration -> Event log' you will find more details about it. You could try to search for event with type 'I' and 'LicenseLimit -' prefix in 'Source' field. Than you can perform appropriate fix steps based on the character of the issue.