It looks like admin accounts in Windows 7 Home Premium have password expiration set on. However, Windows 7 in Home Premium edition does not have a GUI tool to remove it. There is, however, a command line tool which allows to do it over Windows Management Instrumentation – its name is wmic.

If you want to remove password expiration do the following:

1. Click on Start button.
2. Type wmic
3. Right click listed program wmic and “Run as Administrator”
4. Now paste this commmand:

   UserAccount where PasswordExpires=TRUE set PasswordExpires=FALSE

5. Confirm change for each account with password expiration.

See Disable password expiration in Windows 7 Home Premium