This is the upgrade version of shake light with all features of the free version with the ability to run in the background anybody can first try the free app and then they can upgrade to it if they want to run without open the app.

Free app to try - https://play.google.com/store/apps/details?id=com.runn.shakelight&hl=en_IN

But there is some exception with phones like - Xiaomi, Huawei, Oppo, Vivo, etc as they are very concern about their phone battery life so they not allow this app to run in the background you can manage it by whitelist this app to autostart from App info or through the system setting.
Else good go ahead and download.