I had purchased Office 365 Personal subscription for my Mac Mini. I want to transfer the same to my HP laptop which is using Windows

I suggest that you contact Microsoft Support about this. Depending on the subscription model you choice, you should have the option to install Office 365 on multiple devices, regardless of OS that they are running.

Get in touch with Microsoft support. There’s nothing we can do here to help you

Please see if the following discussion can help you: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_install-mso_win10-msoversion_other/using-microsoft-365-personal-on-multiple-computers/08d4e280-7807-4c80-bea1-9aea71d51565