Product Key, not ID, is what you need:

The W98 ProductKey is generally found on the Windows user manual, the
certificate of authenticity, a sticker on the PC or a sticker on the sleeve
or jewel case the Windows CD came in.  The Key also might be available from
the system.

If the system is working in either safe or normal mode:

Open regedit.exe to this key and look in the right pane for the entry
ProductKey:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion

If the system is not working, start the computer with a floppy startup disk.

At the A: prompt, type:  C:\Windows\Command\Find /N "ProductKey"
C:\Windows\System.dat
(Note:  ProductKey must be typed in upper and lower case letters as shown
and there is a space after:  "Find"     after:  "/N"    and after:
"ProductKey"

If the hard drive has been formatted, US customers can contact Microsoft at:
1 800 642-7676.  They will issue retail and OEM product keys after verifying
data located on the W98 CD.

FBTW3 - MHJ94 - 2P9D6 I have lost my