Memorization or Cast On The Fly
A chapter has the option to use spell memorization as per the NERO 8th Edition Rulebook, or the equally acceptable Cast On The Fly (COTF) system.
In COTF when a character would normally study to memorize his spells for the day he studies his spell book and from that point on they can cast any spell which was in the spell book they used to study from as long as they have an unused spell of that level.
If a particular spell was not initially available and later is found by the player they may take ten minutes to study in game and then add that spell(s) to those they may cast that day. There is no requirement to carry a spellbook constantly in order to use COTF.
A chapter using COTF may chose to limit the use of particular spells
by its NPCs, for example: A chapter may decide that they wish to limit the
number of times an NPC may cast dispel magic and even though a particular NPC
has four 8th level spell slots they may be instructed to never use more than
one as a dispel magic.