Some steps may be different, depending on the device model and version of the operating system.
Kaspersky Safe Kids has the following known issues and possible solutions on XIAOMI devices:
The app may stop working in background mode, even if it is locked in memory. To fix this, change the app activity control settings in the battery settings.
For example, on Xiaomi Redmi Note 3 with Android 6.0.1, go to Settings > Battery and Performance > Manage apps battery usage > Choose apps (available if the power saving mode is on) > Kaspersky Safe Kids > No restrictions.
Kaspersky Safe Kids might not restart after the device is restarted or the app is unloaded from memory. To fix this, go to the device's Security Center and allow autorestart for Kaspersky Safe Kids.
On devices with the local Chinese version of MIUI firmware (with no pre-installed official version of Google Play services) the Premium version of the app may be unavailable for purchase.