Dear all,

I have a SharePoint 2013 on Windows Server 2008 R2.

And I create a develop site to share my apps.

First, I try to activate the app permission, but it fail.

Is anybody knows how to fix it?

Thank you!

Workflows can use app permissions feature is only going to be activated if 

1) You have configured your workflow manager properly. Make sure there are not issues with your workflow manager and you can create workflow using SP 2013 Workflow Manager.

2) You have configured apps for SharePoint 2013. Again you will need to make sure that you have hit all the check when configuring SharePoint 2013 apps. 

Follow these two articles to make sure that you have configured apps for SharePoint 2013.

http://technet.microsoft.com/en-us/library/fp161236.aspx

http://sharepointchick.com/archive/2012/07/29/setting-up-your-app-domain-for-sharepoint-2013.aspx

If you have confirmed that both of the above features are configured properly then check your ULS logs and find the detailed issue using the Correlation ID.