readied? memorized? shmemorized?

[Mirabai]

What is the difference between readied and memorized spells? When I add a spell to an NPC caster it labels it as "readied". However, there is also a column for "memorized", which is a number from 0-whatever. So what does this mean?

[NickD]

I'm guessing it's the number of times they can cast (have memorised) the spell.