Good question! Yes, the carbonating bottles expire.
The bottles can't be used for carbonation forever and have an expiration date printed on the bottle. Make sure to check the expiration date and care information on the bottle before using.
Old bottles can still be used to store sill water, but if you want to dispose of the bottles, all parts of the carbonating bottles except for the seal inside the cap are recycable. Please check with your local recycling authority for more information on sustainable disposal options.