Probably a beetle grub, turn it over and see if there are 3 pairs of prominent legs near the head.

I didn't see any legs.

Then perhaps fly larva that would have tiny legs on most body segments. The key to identifying most of these soil larvae is a view of the underside.

Javier, do you know what kind of plant used to be in the container?

Your larvae looks like a root weevil larva, perhaps. They are described as being legless, as are most fly larvae.

I don't have any ideas about the plant type. It was dry when first see it last summer. i throw it away and start to discover these larvae and many small millipedes in the pot. I want to plant something else in the pot and was wondering what to do with the dirt in there.

Should i throw it away and get rid of the larvaes?

Yes, I would dispose of the soil in the pot and begin with a fresh potting mix.

Thanks, Ive take no chance and replaced it