SharePoint The Subscription Settings service and corresponding application and proxy needs to be running in order to make changes to these settings

When you are working with sharepoint usually you need to configure the APP url in Central administration.

But when you click on the Configure App URL section in Central administration you will get this URL.

Root Cause :

This is expecting A new service application created on its dedicated App Pool is required to be created in SharePoint.

This Can be achieved with PowerShell scripting.

Here is the Piece of code ( This has taken from MS reference documents Change it according to business needs ):

You must runt this powershell and make sure you change the Managed account name in the script.

Run PowerShell as Administrator

add-pssnapin "Microsoft.Sharepoint.Powershell"

$manaccount = Get-SPManagedAccount SP2013Server\Administrator

Remove-SPServiceApplicationPool -Identity SettingsServiceAppPool

$appPoolService = New-SPServiceApplicationPool -Name SettingsServiceAppPool -Account $manaccount

$appService = New-SPSubscriptionSettingsServiceApplication -ApplicationPool $appPoolService -Name SettingsServiceApp -DatabaseName SettingsServiceDB

$proxyService = New-SPSubscriptionSettingsServiceApplicationProxy -ServiceApplication $appService 

This will create a service application in Sharepoint then you can configure the URL in CA App section.