Travellers arriving into Flåm and not staying the night will require somewhere to deposit their bags if arriving by one mode of conveyance and leaving via another, as many do. This, off course, assumes you have some time for a look around before leaving.
This need is well catered for with a left luggage facility (a red shed) right by the railway terminal and within a few metres of where one boards or disembarks fjord tour boats.
The left luggage facility is open daily 8am to 8pm and charges (August 2015) NOK40 per piece of luggage for same day storage while overnight storage costs NOK80.
If you stay overnight in Flåm village you will be able to leave your luggage at your lodgings until you leave. As all the village hotels, etc are within 300 metres of the train station/ ferry terminal/ bus area you will not need to put your bags into the left luggage facility on check out. You can easily go get them when you are leaving.