During a recent Microsoft True-Up piece of work we were doing at work we discovered that 3 of our Microsoft SQL servers had been installed with the Developer edition of Microsoft SQL 2008 R2, this isn’t really an issue because we are licensed for the proper versions but to make life easier for us in the future we decided to upgrade the instances to the correct version now rather than run into this same issue again in the future.
Now there are a couple of ways of doing this but both methods require the installation media and the PID from the target version to hand.
In this guide I will be upgrading from SQL 2008 R2 Standard to Enterprise Edition.
GUI Wizard Upgrade
The first of the upgrade methods uses the Installation Wizard to carry out the upgrade.
Run the Setup.exe file to bring up the Installation Wizard.
Click onto the Maintenance Option and click Edition Upgrade.
Click through a couple of Setup Rule screens.
At this screen you need to enter the new Product Key for the version of SQL that you want to upgrade to.
Accept the license terms.
Select the SQL Instance to upgrade.
Run through the Upgrade Rules check.
We can see that we are going to upgrade to Enterprise edition in this screen.
After a few minutes the upgrade was complete and launching SQL Management Studio and checking the properties now shows an upgraded SQL Server.
Command Line Upgrade
Open up a command prompt and browse to the folder containing the SQL Server Installation media.
Run the following command to upgrade the edition of SQL.
Setup.exe /q /ACTION=editionupgrade /INSTANCENAME=MSSQLSERVER /PID=”<PID key for new edition>" /IACCEPTSQLSERVERLICENSETERMS
In a matter of seconds your version of SQL Server will change to the required version.
A much quicker and simpler way of upgrading the edition of SQL Server 
