GSD puppy ears frequently will be "lazy" early in their lives due to teething. Their bodies are using their calcium for teeth development instead of developing ear structure.
If his ears have not been standing up to this point, you do need to think about taping the ears. Usually by 5 months they have been standing on their own at least a portion of the time.
There are varying opinions on whether taping works or not, but the majority state that it works well if started before 7 months of age. Most also agree that if a pups ears are not standing some of the time by 5 months then taping is recommended. It can take as long as 2-3 months to achieve results. Now I know you have been taping for two months so far, but I'm not sure which method has been used, so you may want to review the sites below and see if another month does the trick. .
Here are excellent sites on ear taping for GSD's and information as to the proper way to do it.
Ear implants are considered elective surgery. There have been some serious infections associated with the implants so many surgeons no longer perform this type of surgery. You would really need to check with surgeons in your area. You can find surgeons by checking the correct box on the following page and putting in your zip code. It will give you a list of surgeons in your area.
Here is a article on implants.
And here is the permastay brand website. If you have difficulty locating one, they may have a list of surgeons which do the procedure. .
Now personally, if you have no plans on showing your dog, I would leave the ear alone. A floppy ear from time to time adds character and individuality to your dog. A floppy ear does not make them any more obedient or change their personality, it is purely cosmetic at this point.
I hope this information is helpful to you.