Hi Guitarroy123.
Which product key are you looking for?
In order to use Office 365 you need to buy an Office 365 subscription: that will give you the license to use it and to install the Office 365 ProPlus desktop applications on up to 5 devices.
I don't know whether HP could provide you with an Office 365 license: read the document at https://support.hp.com/us-en/document/c04573043.
Bye.
Luigi Bruno
MCP, MCTS, MOS, MTA