Here God's commands are spoken of as if they were objects that someone could put into a storeroom. AT: "memorize my commands" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The apple of the eye is the pupil inside the eye, which people normally instinctively protect when an object flies at their face. Here "the apple of the eye" represents whatever a person values and protects the most. AT: "as your most valuable possession" (See: [[rc://en/ta/man/translate/figs-idiom]]).
Possible meanings are 1) that the writer wanted his son to engrave certain commands from God on a ring and wear it, or 2) that the writer wanted his son to always remember God's commands, as if he always wore a certain ring. (See: [[rc://en/ta/man/translate/figs-metaphor]])
# write them on the tablet of your heart
Here the heart represents a person's mind, and remembering something well is spoken of as if the person were writing it on a stone tablet. See how you translated this in [Proverbs 3:3](../03/03.md). AT: "remember my commands well as if you were writing them in stone" (See: [[rc://en/ta/man/translate/figs-metaphor]])