When can we stop sterilising baby's bottles and pump parts?

My friends mostly stopped when their babies are between 8 months and 1 year old. They would clean the stuff with soap after every use. Once every one to two days, they would soak the bottles and parts in hot soapy water for 10-15 minutes, and scrubbing those to remove any "grease".

No hard and fast rule though. Had previously sterilised till baby turns 2 years old for bottles. I usually sterilised my pump parts each and every time after I pump. So if I pump more than 2 years, the bottles would also be sterilised more than 2 years.