From C:\> runas /?:
/savecred: to use credentials previously saved by the user.
This option is not available on Windows 7 Home or Windows 7 Starter Editions and will be ignored.
If you are not running a Home or Starter edition of Windows 7 please update your question to provide more details on your version and network setup.
Additionally, /savecred is ONLY for the user who ran the Runas /Savecred. So if you use Savecred, and give the password, you won't have to enter it again, but other users would have to repeat the /savecred, and enter the password, to have the credentials saved for their use.
You can see which credentials are cached in the Windows Credential Manager (Control Panel>User Accounts>Credential Manager)