Onlife will update you each and every time your calendar items are Created, Updated or Deleted.
These are called CRUD alerts (CReate, Update, Delete)
So how does this work? Let's say you've been invited to an event, but the event host has changed the time. You'll get a CRUD alert letting you know of the change.
These alerts will be sent directly to your phone lock screen, letting you know of any changes to your schedule immediately it happens.
Make sure you have notifications turned on. You can check this in your Onlife app settings:
Settings > Apps > Onlife > Notifications - ensure Allow Notifications is turned on and the three options ticked (lock Screen, Notification Centre, Banners)