The full message of the error you may encounter is:
RegistrationError: {Service}: Maximum number of unregistered requests exceeded. Your request was authenticated using {an HTTP request parameter|a cookie|an IP address|a SOAP header}. Your username is {username}. Please visit http://www.xignite.com/registration-help for more information.

There are two reasons for encountering this error:
1. You are not properly authenticating your calls. To fix this issue, make sure that you are logged in to your account (for authentication via "Cookie"), or using the correct API token (for authentication via "API Token")
2. You do not have an active subscription to the data you are trying to request

Please reach out to support@xignite.com if you continue to receive this error, and it is not due to the reasons highlighted above.