where do i add serial numbers on my account
You use Native Access for that. For hardware you can also use this link: https://www.native-instruments.com/en/support/hardware-registration
Serial numbers for what? If you have a Native Instruments account, and you bought Native Instruments software from the Native Instruments web site, you don't need to add the serial number(s).
In general then as already written by maniacintosh81 then to add serials to your account then you use the Add Serial function in lower left side of latest version of Native Access for your OS.
If there is a problem adding the serial to your account then you will need to contact N.I. Support (all) .
In case that you need guidance contacting support : How to contact NI Support and How to get in touch with our Customer Care .
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