upgrade windows 2008r2 standard to enterprise to upgrade memory usage
Windows Server 2008 R2 includes a command-line tool called the Deployment Image Servicing and Management tool, or DISM. It’s functionally equivalent to the Windows Anytime Upgrade feature in client versions of Windows. You can run it from an elevated command prompt.
To determine the currently installed edition:
DISM /online /Get-CurrentEdition
To determine the editions you can upgrade to:
DISM /online /Get-TargetEditions
To actually perform an upgrade:
DISM /online /Set-Edition:<edition ID> /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX