Method 1
wmic /namespace:\\root\CIMV2\TerminalServices PATH Win32_TerminalServiceSetting WHERE (__CLASS !="") CALL GetGracePeriodDays
Method 2
$obj = gwmi -namespace "Root/CIMV2/TerminalServices" Win32_TerminalServiceSetting
$obj.GetGracePeriodDays()
Method 3
(Invoke-WmiMethod -PATH (gwmi -namespace root\cimv2\terminalservices -class win32_terminalservicesetting).__PATH -name GetGracePeriodDays).daysleft