it's better to shoot it all out because if the temperature changes then the paint goes bad.. I would suggest to keep it somewhere in a dark kitchen cupboard where there is little light and temperature change..
Never keep paint from events. In the unlikely situation I have any left over it's just kept in my kit bag and used for testing, target practice or snapshooting drills.
I swear this isn't spam lol, I have posted a lot within the couple of days that I was very active but I can assure u it wasn't spam I just though it would be a little more active