Second example:
Heat Metal
Transmutation [Fire]
Target: Metal equipment of one creature per two levels, no two of which can be more than 30 ft. apart
I cast Heat Metal on the metal equipment of three creatures, who are standing in a triangle, twenty feet apart from each other. On his action, one of the creatures moves twenty feet further away from his friends.
The three creatures no longer satisfy the "no two of which can be more than 30 ft. apart" condition of the target line, which means that the metal equipment each of them carries is no longer a valid target for a Heat Metal spell aimed at all three.
What happens to the spell?
1. Nothing. It's already in effect - the relative positions of the creatures is no longer important.
2. The equipment of the creature who moved is no longer affected, but the equipment of the other two continues to heat up as normal.
2a. The spell is suppressed on the equipment of the creature who moved, but if he returns within 30 feet of the others, he'll suffer the normal effects.
3. The spell terminates.
3b. The spell is suppressed, but if the creature returns, the equipment of all three will be affected again.
-Hyp.