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

I was working on hosted app when I encountered below error:

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


Solution:

Copy and paste below script in SharePoint Management Shell.

$acc = Get-SPManagedAccount <AccountName>
$appPool = New-SPServiceApplicationPool -Name "<Application pool name>" -Account $acc
$app = New-SPSubscriptionSettingsServiceApplication –ApplicationPool $appPool –Name "Subscription Settings Service Application" –DatabaseName <Database name>
$proxy = New-SPSubscriptionSettingsServiceApplicationProxy –ServiceApplication $app

Where
   Replace your <AccountName> with managed account
   Replace your <Application pool name> with Subscription Settings Service Apppool

   Replace your <Database name> with SPMT_Settings_Service_DB  

Reference:
https://technet.microsoft.com/en-us/library/fp161236(v=office.15).aspx