1. Click Management
2. Click AddressFinder (NCOA)
3. On the right side of the next screen (under the About AddressFinder section), you should see a section for "Most recent results" that will display the date for when this service was last run...
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If that section ("Most recent results") is missing from that screen in your organization's database, then that means that your organization has NOT successfully run this service yet.

*Note: Please see the following resource for more information about what might have caused a recent NCOA run attempt to not complete successfully: Why did nothing happen when I scheduled AddressFinder (NCOA) to run overnight?