How long does the effect of lip fillers last?

I have a complex about having small lips, so I'm thinking of getting lip fillers.

The price is relatively low, so I try to maintain it regularly if possible.

But how long do lip fillers usually last?

I'm also curious about how to maintain it to extend the duration.

Since this is my first time getting fillers, I don't know much about it.

I've heard that lip fillers usually wear off faster than those in other areas... I guess it's because of all the movement...?

I would like to know if getting multiple filler injections makes the effects last longer, or if they wear off faster.