They can either go in the fridge or be washed with soapy water between uses. They must be sterilised once every 24 hours of being used. Tbh I put the collection bottle/ cup parts in the fridge and wash the flange/ breast plate just because personally I donāt like it being quite so cold on my skin
I put it in the fridge when Iām done pumping multiple times a day and just sterilize at night when I wash/sterilize all my bottles! My lactation consultant said this is fine to do :) itās made life so much easier and my daughter is 6 months and healthy