If you are not sure to be able to use the cmdlets, you can have a look at this article.
1. Launch SharePoint 2013 "Management Shell"
2. Get the Farm account
$account = Get-SPManagedAccount FarmAccount
3. Create a new application pool using this account
$appPoolAppSvc = New-SPServiceApplicationPool -Name AppServiceAppPool -Account $account
4. Create the "App management" service application, using this application pool
$appAppSvc = New-SPAppManagementServiceApplication -ApplicationPool $appPoolAppSvc -Name AppServiceApp -DatabaseName NomDeLaBDD
5. Create a proxy for the service application
$proxyAppSvc = New-SPAppManagementServiceApplicationProxy -ServiceApplication $appAppSvc
6. Start the "App Management Service" service
Get-SPServiceInstance | where-object {$_.TypeName -eq "App Management Service"}
(Get-SPServiceInstance | where-object {$_.TypeName -eq "App Management Service"}).Provision()
1. In SharePoint 2013 central administration, click on "Application Management", then on "Manage Service Applications"
2. Click on "New", then on "App Management Service"
3. Type a name for the service application and its database
Type a name for the application pool and the account used by the pool.
Uncheck the checkbox if you do not want to create a proxy for the service application, then click on "OK".
4. The service application and its proxy are created
5. The last action is to start the "App Management Service" service.
Click on "Application Management", then on "Manage services on server"
6. Click on "Start" in front of the service