Boil (or better yet, pressure cook) the jar and the lid, and then let it cool. Use the sterile water to use for the wash, and the jar and lid will be sterile for storage.
Fill the jar to overflowing with your yeast slurry, cap and label, then place in the fridge for many months of storage.
When you open the jar, either flame the mouth, or use sanitizer. I wash the entire jar and spray with sanitizer prior to opening, and then flame the mouth before pouring.