YOu can just store them in their pots over winter if they're indoors, but Oriental lilies are usually fully hardy anyway - though you wouldn't want the pot to freeze.

You might find that the compost in the pots is quite wet, in which case the bulbs could rot over winter. If they were mine, I would unpot them, allow to dry off, clean them and then repot in new compost that I would keep 'just moist' until they start into growth. This would mean keeping them under cover but the nearly dry compost will not freeze so quickly.

I usually lift mine now. check them for vine weevils [found 3 today] clean them then repot in fresh compost. they then sit on the path outside over winter. I do the same with the gladioli and keep them in the unheated greenhouse.