SQL Server 2012 Upgrade from Standard Edition to Enterprise edition
Step 1- Identify SQL executable file , Right click and run as admin
Step 2 – click on Maintenance tab on left hand side.
Step 3- Click on Edition Upgrade
Step 4 – Click Okay
Step 5- Click Next
Step 6 – Click next on Production key
Step 7 – Click check on “I accept the License terms” and then click Next
Step 8 – Select Instance you want to upgrade form “Specify the Instance of SQL Server” and click next
Step 9 – Click next
Step 10 – Review upgrade and click Upgrade
Step 11 – Click Close
Step 11- Open SSMS and check version.