We’ve noticed Overwolf API events stop firing if the Overwolf client is closed/restarted while a game is already running. The game must be restarted to resolve this.
As long as the Overwolf client is working, your info updates will be kept updated (match id, accumulated kills, etc.), even if your app is closed, since the GEP (game event provider, the component that collects this info) is still working behind the scene.
The things that not kept are real-time events (like kill, etc.). If you close/restart the OW client, then ALL the info is cleared. Including the info updates like the match id, etc. This is essential info so the app can’t work without it.
Because of the above, if you restart the client during the game - probably your app will not function correctly until you start a new match.