We have private app store, so we don't need to set target sdk 26(oreo) or higher.
Then if i set target sdk 25 to my app, then will it not have Ore Background limit even in OREO phone?
As specified on this page: https://developer.android.com/about/versions/oreo/background
Android O's background execution limits do not apply by default to an app that targets an sdk lower then 26, however it is possible for the user to manually impose these restrictions on older apps by going to settings.
As qouted "Note: By default, these restrictions only apply to apps that target Android 8.0 (API level 26) or higher. However, users can enable most of these restrictions for any app from the Settings screen, even if the app targets an API level lower than 26."