From what I understand the lexeme or lemma of a word carries the sense information of the word, and hence for an inflected form like tablets, it can have a different lemma, each one for each sense of the word.
But does the inflected form "tablets" have multiple stems ("tablet" and "tablets"), or is it just the stem "tablet". i.e. does it only have 1 stem irrespective of the number of senses the inflected form carries?