Assuming that no previous installations of the app exist, if an end-user installs your app on a second device they will be issued with a fresh License Key by the License Get request and will be issued with free in-app credits, if enabled for that app. Unfortunately there is no way to detect when the same user is using different License Keys on different devices, so free in-app credits (if applicable) can not be limited to individual users - only to devices. You can optionally allow your end-users to update their installations on multiple devices to use the same License Key.