Do I need both KSE and Runtime

@parul.dang During the initial release of Katalon Enterprise it was confirmed by Katalon team that KS < 7.0 Will continue to work till April 2020 but there will be no support to them in terms of fixes.

Else you can always use KS > 7.0 ( Non Enterprise version ) which is free but with certain limitations.

https://docs.katalon.com/katalon-studio/docs/license.html#katalon-studio-license-types