We are happy to share that the 6 months replacement period is an international practice (from general plastic manufacturers) as the first 6 months of baby's life is when heavy sterilization and washing are conducted. As such, plastics in general may be prone to wear and tear.
However, as Hegen's bottles are made of Polyphenylsulfone (PPSU), a FDA compliant food-contact grade material widely used in the manufacturing of medical appliances, it is able to withstand higher and/or more frequent usage due to its superior toughness and high temperature resistance and may not wear out as soon as compared to other types of plastic.
As such, mummies may repurpose the bottles for other uses well after the general plastic replacement period so long as the PPSU is in a good condition.