Getting results from your singing lessons takes time. Don’t get discouraged. It took me years to get the quality of voice I have now, and I still take vocal lessons.
Your voice can maintain for as long as you are alive if you do it correctly. There are professional singers who really understand this. These singers have always had a coach because they know their voices are continually growing and developing. This is no different than developing the physical coordination it takes to be very proficient at learning to play an instrument. Your voice is an instrument. I am constantly learning more and more things about my voice. I am almost 50 and I’m doing things with my voice now that I could never do when I was 20 or 30 or 40! Most people think your voice deteriorates as you get older….but that doesn’t have to happen!
Your voice is going to change over time, especially if you are performing. You need to keep this in check. Doesn’t matter what style you are singing. It takes time to develop good habits so don’t stop. Everyone can have a great voice. Don’t get in your own way to your ultimate goal….don’t get lazy….you can do it! Yes, it takes time….and enjoy the journey!