How to keep yuzu or sudachi juice.

The easiest way is to freeze the strained juice in ice cube trays. I use small silicone cube trays to arrange small cubes of yuzu juice.
 These juices contain between 0.6 to 3.2% glucose, fructose and sucrose (the last two being the majority) which makes them sticky.

https://www.jstage.jst.go.jp/article/jjshs1925/73/3/73_3_293/_pdf/-char/ja

The small cubes are really easy to remove from the tray, easier than large ones. I put the ice cube trays in the freezer and I always have yuzu or sudachi juice for fresh ponzu, sauces or drinks.