Congratulations on celebrating such a wonderful milestone! By no means is being 50 a disqualifier for breast augmentation. Good candidacy is left to your overall health, genetics, the health and condition of your skin and breast tissue, as well as your expectations. I’d also recommend getting medical clearance from your primary care doctor beforehand.
You may have different goals for the breast augmentation surgery than a 20 year old would. For that reason, I suggest that you be very open in what you are looking for and what your goals are with your surgeon. I also recommend asking if they have experience doing breast augmentation with women in your age range. Last, if you have any concerns regarding skin laxity, I’d also consider discussing the possible necessity of a breast lift to compliment your augmentation.