Lexical vocables are produced; functionalized vocables survive. We can give a positive account of the conditions under which a vocable remains lexical, and in the absence of those conditions lexical status cannot be sustained. Functionalization is a special case from the consequence of attenuation in which lexical language assumes a new non-lexical structural role. Sometimes an additional use does not interfere with its earlier role and indeed is morphologically and prosodically indistinguishable from it. Consider going in its use in progressive tenses, which coexist with its uses as a verb of process and motion. Consider the two presentationally indistinguishable uses
I'm going to shop one of which (lexical going) characterizes a present departure or motion, and one of which (functionalized going) registers an intention. Contrast the distinguishable uses of have
I have already shopped and
I already have my outfit, or those of used I used my time wisely and
I used to use my time more wisely
These examples demonstrate that particular instances of verbs can acquire auxiliary functional roles in certain syntactic environments, without eradicating early uses.