The second entry on the SERVER line is the hostname of your computer. Make sure the hostname entry matches the actual hostname of the system (see step 1). The hostname entry is not tied to your keycode, and may be changed as long as it matches the hostname of the system that runs the license manager.
The third entry on the SERVER line is the Sentinel Key number. This number should match the number returned by running Start > Programs > ArcGIS > License Manager > Display Hardware Key Status. Occasionally, the number printed on the Sentinel Key does not match the number returned by checking 'Display Hardware Key Status'. In this case, use the number returned by 'Display Hardware Key Status' to request new licenses. Notice this number always starts with a '3'. For example, if the e-mail tool used is Microsoft Outlook with Microsoft Word as the e-mail editor, all instances of '=3' will be stripped from the license file(s), as '=3' is a special Microsoft Word programming code. In such case, edit the license file(s) to restore the '=3'.
The last item on each FEATURE line is the checksum number. The checksum number can also be stripped of a '=3'. The entry should contain 'ck=' followed by a number. If the equal sign is missing, the number three will also be missing. In such case, edit the license file(s) to restore the '=3' in the checksum number.
Use the key with the number that matches the ESRI_SENTINEL_KEY number in license file.
If you do not have that hardware key, confirm the ESRI_SENTINEL_KEY number of the hardware key you do have and then contact ESRI Customer Service for the appropriate keycodes.