The following URL can be used in order to quickly check the licensing of an app.
https://apps.kwizcom.com/Products/Settings/License.aspx?SKU=APLFE&InstanceID=9334b9be99asd239f99cae7f57daf75&Login=user@domain.com
SKU = The SKU of the product and should be 4 or 5 letters
InstanceID = The unique site ID of a site or site collection
Login = the email that is used to log into the SharePoint site