This tool may help.
https://www.nirsoft.net/utils/product_cd_key_viewer.html
you can also try contacting the reseller but doubtful they would have a record. The other option is to contact the activation center directly.
--please don't forget to Accept as answer if the reply is helpful--
Regards, Dave Patrick ....
Microsoft Certified Professional
Microsoft MVP [Windows Server] Datacenter Management
Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.