An NPC never cares about LA. Only CR determines experience rewards. Consult this question for how to figure out an NPC's CR.

As per Improving Monsters:

Challenge Rating

Most templates increase the creature’s Challenge Rating. A template might provide a modifier to be added to the base creature’s CR, or it might specify a range of modifiers depending on the base creature’s original Hit Dice or CR.

While an NPC technically does have an ECL (which is what LA is factored into), the NPC's ECL never matters. From reading the monster entries:

A character’s ECL affects the experience the character earns, the amount of experience the character must have before gaining a new level, and the character’s starting equipment.

An enemy NPC doesn't care about any of these things, since he doesn't earn XP nor level up.

An NPC never cares about LA. Only CR determines experience rewards. Consult this question for how to figure out an NPC's CR.

As per Improving Monsters:

Challenge Rating

Most templates increase the creature’s Challenge Rating. A template might provide a modifier to be added to the base creature’s CR, or it might specify a range of modifiers depending on the base creature’s original Hit Dice or CR.

While an NPC technically does have an ECL (which is what LA is factored into), the NPC's ECL never matters. From reading the monster entries:

A character’s ECL affects the experience the character earns, the amount of experience the character must have before gaining a new level, and the character’s starting equipment.

An enemy NPC doesn't care about any of these things, since he doesn't earn XP nor level up.

An NPC never cares about LA, and always uses CR. Consult this question for how to figure out an NPC's CR.

As per Improving Monsters:

Challenge Rating

Most templates increase the creature’s Challenge Rating. A template might provide a modifier to be added to the base creature’s CR, or it might specify a range of modifiers depending on the base creature’s original Hit Dice or CR.

While an NPC technically does have an ECL, the NPC's ECL never matters. From reading the monster entries:

A character’s ECL affects the experience the character earns, the amount of experience the character must have before gaining a new level, and the character’s starting equipment.

An enemy NPC doesn't care about any of these things, since he doesn't earn XP nor level up.

An NPC never cares about LA. Only CR determines experience rewards. Consult this question for how to figure out an NPC's CR.

As per Improving Monsters:

Challenge Rating

Most templates increase the creature’s Challenge Rating. A template might provide a modifier to be added to the base creature’s CR, or it might specify a range of modifiers depending on the base creature’s original Hit Dice or CR.

While an NPC technically does have an ECL (which is what LA is factored into), the NPC's ECL never matters. From reading the monster entries:

A character’s ECL affects the experience the character earns, the amount of experience the character must have before gaining a new level, and the character’s starting equipment.

An enemy NPC doesn't care about any of these things, since he doesn't earn XP nor level up.