The answer to this question is YES. Your results cannot change and go back to how it was before the surgery. Rhinoplasty surgery (known as nose job), provides life long results. Of course, until the patient reaches the final result 1 year post surgery, the nose shape will change and will settle in its place.
Unless you try non-surgical nose job, which is performed via fillers, the results will be permanent. As filler material is used in this treatment, and as the filler dissolves over time. The results will not be permanent.
However, after a rhinoplasty surgery in the long term, so around 20 to 30 years, as you will continue to age, your total face will change and become saggier and looser due to collagen loss, the skin over the nose will change as well. If you compare your facial look according to your 20s and your 30s, you will even see a difference there. So, the change of rhinoplasty results will change according to your aging process, otherwise, the results are of course permanent.
If you are going through a rhinoplasty surgery under general anesthesia performed in the hospital, your nose shape will definetly permanently be changed. But, for example, you have had a outside impact to your nose, like you had an accident, or fell down, hit your nose etc. If this caused trauma is severe, a revision surgery might be necessary. However, generally traumas on the late post period like 2 to 5 years, mostly the nose does not really react to the trauma because the new result has settled in its place. However, this depends on the severity of the recieved trauma, for example if you have been in a very severe car accident, maybe you would be in need of a revision.
Another issue here that we should point out is the thickness of your skin. This might effect your results negatively in the long term while you age, because the thicker (heavier) the skin is, the looser it will become. So, this is going to effect effect the skin over the nose to become loose as well. But these issues can occur only in the very very long term post surgery.
The technique being used effects the results to be fail in the long term as well. So, it is very important for you to do your research before deciding on your surgeon. But, as new techniques are being developed and also as there are new technological innovations being involved, the results are becoming more and more permanent. The older techniques that were applied around 10-15 years ago might have caused an alar collapse or a minor hump to reform. Nowadays, these issues are not really encountered.