Can I continue getting facial fillers forever as this is what I want?

Great question.  You can absolutely use fillers long term.  Whether you're using hyaluronic acid fillers or a combination of HA and permanent fillers, I would caution against relying solely on them.  We tend to forget that we can stimulate our own collagen and elastin with the right technologies.  It's usually a combination of procedures (fillers, laser, radiofrequency, neuromodulators) that keep us looking youthful but, more importantly, natural.  I hope this helps! Dr. Dima

There should be no harm in continuing facial fillers for an indefinite time.  The fillers that are FDA-approved are safe over the long term.  

Currently, there is no evidence that there is a problem with repeating fillers.   Generally, think of fillers as short term: 6-12 months Juviderm and Restylane, longer term: Radiesse, Sculptra (2-3 years), and long term / semi permanent Bellafill.  
Restylane and Juviderm are hyaluronic acid and these get digested by the body over time and the affect dissipates away over time. Most are FDA approved to last 6 months.  Numerous variants on hyaluronic acid fillers are available with slightly different features based on cross linking and size of molecular size of individual particles.
Radiesse is a biostimulant that promotes collagen but breaks down over time (2-3 years)
Sculptra is a bulk filler biostimulant as well very similar to material in some absorbable suture.(2-3 years)
Bellafill is a biostimulant using polymethyl methacrylate (PMMA) beads.  These stimulate collagen but do not get broken down my the body.  This is why this is considered a semi-permanent filler. (FDA > 5 years)  Bellafill is the only filler approved for acne scars with 5 year follow up data to support effect.
Nearly all fillers are FDA approved for nasolabial folds but many off-label uses are commonly performed. One key to remember is that the biostimulant fillers are making collagen which is thicker/less pliable which makes the hyaluronic fillers better for less dense tissue tissue such as the pink are of the lips.   
As of now, no biostimulant filler should be used on the pink part of the lip/vermillion. Biostimulant fillers also do not have a reversal agent such as hyaluronidase used on Restylane or Juviderm. Steroid injections can non-specifically reduce biostimulant fillers.   The hope would be that reversal agents are not necessary as this defeats the filler placement.

I have many patients who are unable to have surgery and are on “permanent” filler regimens. Fillers keep improving and you may be able to use some of the newer, long lasting ones to great success.

There should be no problems with continuing facial fillers. There are 2 things you need to know about them, however, and an alternative. First, though we did not think so initially, we now know that essentially all fillers are collagen stimulators. Sculptra and Radiesse were thought to be the only ones that created new collagen, but hyaluronic acid fillers have now been shown to do so also. This means that for any one problem, you never have to fill it with the same amount you did the last time to achieve the same result, meaning that you can concentrate some effort elsewhere. Secondly, the newer fillers like Juvederm Voluma last significantly longer than previous fillers. In the cheek, I have had it last over 4 years in a number of people. As for the alternative, there is always your own fat, which is a "permanent" alternative, meaning that you will lose some, but only that that you would have done naturally. Either way, you need an an expert.