Edition upgrade in SQL Server:
Many times my project client did ask me to install Express edition and later on they buy the license and ask me to install the Standard edition.
Here we go with upgrade steps ahead with screen shots:
Download the Standard edition or Enterprise edition software which you want to upgrade as destination new edition.
Start the installation and on
Screen 1: Click Maintenance
and then Click Edition Upgrade and follow the screen shots.
Provide the license Key of the edition:
See the summary clearly, where edition upgrade is mention at the first. Cross check and then go for upgrade.
Hope the above information helps.
let me know for further more help