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A survey or vote macro can be restricted to voting only by users in certain groups and/or only users on the list of those allowed to vote. These restrictions are set in the macro parameters when creating/editing a survey or vote macro. That feature has always existed. The new feature is that you now have the option to ignore existing votes from users who voted in the past but have since been removed from an allowed group or have been removed from the list of approved voters.
See the screenshot:
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Related Documentation
Easy Forms Server and Data Center - User Guide