2.5 weeks post-op. Why is my lip filler so malleable? (photos)

Hello and thank you for the question. At this point, you should be seeing the final results of your lip filler treatment, so if you are unhappy with your outcome, it may be time to schedule a follow-up appointment. You can see your original injector or another board-certified dermatologist for an in-person assessment and further treatment recommendations. The good news is that if your lip filler is not producing the desired results, you should be able to have it dissolved and undergo a new procedure to produce a better outcome. 

The filler may still be malleable as it appears it was placed superficially.  Your injector can dissolve the filler bump with hyaluronidase.  This should help the overall look appear smoother.

Great Question! 
The answer to "how long can it be malleable" is, "it depends"! It depends on where the filler was placed.
This filler looks like it is more superficial, that's all fine if all of the filler was placed in the same plane [location] because then it wouldn't have anywhere to go. 
Treatment options are as follows: 
You can add a thin coat to that plane, OR 
The injector can manipulate and move it deeper by hand [this will hurt]  OR 
He/She can inject a TINY amount of hyaluronidase into this small pocket... but I STRESS VERY SMALL to just dissolve this little pocket.
Good Luck!