I think you’re asking about the WSUS SID. According to the following link, there are a few registry values that store this information.
https://gallery.technet.microsoft.com/scriptcenter/Reset-WSUS-Authorization-2e26d1b0
Registry values to look at:
HKLMSOFTWAREMicrosoftWindowsCurrentVersionWindowsUpdate
PingID
AccountDomainSid
SusClientId
SusClientIDValidation
BatchPatch can retrieve registry values from target computers using ‘Actions > Get information > Get registry key/value’