Theres no real evidence that it will impact future production, but theres also no real evidence that it will provide any value beyond placebo effect either at your age
I agree, Easy-motha-f
uckin'-E.
I think we can safely delegate so-called "testosterone enhancers" into two categories, based on their methods of action: compounds that seek to enhance total testosterone biosynthesis, and compounds that seek to increase the potency of previously biosynthesized testosterone [via AR upregulation, SHBG inhibition or what have you]. As you know, both of these processes are rate-limited, by either gene coding and/or enzymatic conversion. For clarification, rate-limited merely means that the rate at which a compound can be produced is limited by a certain aspect involved in its production. As age increases in males, testosterone production deteriorates in a linear fashion with the proliferation of these 'rate-limiting' factors - as a result, compounds which eliminate or significantly reduce rate-limiting factors have substantial effects on increasing steroidogenesis, or its effects, in older males. In young males, however, hormone production is very much optimized already; the male body has evolved just in case our hormone production is optimized, our physical capacity is optimized at the same period, to increase mobility and chances of reproduction.
In essence, the eighteen year-old hormone production-system is most likely very near 'peak capacity', such that the minor increases in testosterone that a "testosterone enhancing" supplement may bring would not significantly impact performance. While natural 'test-boosters' are wonderful compounds, there is a biologically-determined ceiling on how much testosterone our bodies can produce under natural conditions - this is why steroids are effective in every case, and the effectiveness of natural-hormonal supplements must be analyzed on an ad hoc [case-by-case] basis!
With all this being said, the vast majority of compounds purported to increase testosterone do so through mechanisms that carry other beneficial effects [cAMP upregulation, Ca2+ channel permeability and so on]. So, while a certain ingredient will not raise testosterone in an eighteen year old male, it may certainly increase performance based on its adaptagenic capabilities.