Solution to error "The serial number does not belong to a known product"

When attempting to activate a library in Native Access, if you run into an error message about your serial number not belonging to a known product, here are the necessary steps to solve the issue: (replacing "[LIBRARY NAME]" with the name of the affected sample library product (for example, "Evolution Rock Standard"):

1. Quit Native Access

2. If you are on Windows, Delete the files (if you see any of them):
"C:\Program Files\Common Files\Native Instruments\Service Center\NativeAccess.xml"
"C:\Program Files\Common Files\Native Instruments\Service Center\[LIBRARY NAME].xml"
"C:\Program Files\Native Instruments\Service Center\NativeAccess.xml"
"C:\Program Files\Native Instruments\Service Center\[LIBRARY NAME].xml"

2a. If you are on a Mac, Delete the files (if you see any of them):
"/Library/Application Support/Native Instruments/Service Center/NativeAccess.xml"
"/Library/Application Support/Native Instruments/Service Center/[LIBRARY NAME].xml"
"/Library/Preferences/com.native-instruments.[LIBRARY NAME].plist"

3. Restart Native Access and add the serial again.