Sandbox version for testing

How do I create a sandbox version of my app for development and testing? Right now all changes are live. It was fine when I just had a couple users, but now that I’ve added more I need to be able to develop and test without disrupting workflow.

@Eric_Silver
You can do it with creating a Stable Version of your app via Manage > Versions and assigning this version to your app users via Users pane.

It this features available only for Business Plan? Or can I use it for my PRO plan app?

@Vlad_Roman
I’m afraid versioning control needs a Business Plan.

When I’m done with developing and testing how do I make that the new Stable version?

It looks like this only works on the Corporate plan. I am on the Premium plan. Any other ideas on how to do this?