As long as you clean them well from time to time, there should be no problem using the glass bottles for a long time

Hello,
as long as they are not damaged, e.g. I dropped one and the top of the thread is chipped or the cap is defective, you don't need to replace them. You may even be able to buy the cap separately.
The plastic bottles should be replaced every 1 to 2 years as soon as small cracks appear.

I hope I have been able to help.

Mfg S. Zavelberg

In my opinion, you don't need to replace a glass bottle. That's one of the advantages of a glass bottle.