BHB Salts (Exogenous Ketones) will simply be absorbed into the blood as ketones. The BHB supplies another source, which doesn’t require the liver to produce ketones. There is no reason that the ketones produced by the product will affect the kidneys or liver any differently than ketones produced from exogenous fats (such as when eating a ketogenic diet) or ketones produced from stored fats (such as when calorie restricting or losing weight). Exogenous ketone scientific literature does not suggest that neither the kidney nor liver function is negatively affected by ketosis.
The major role of the kidneys when it comes to ketones is to excrete excess ketones in the urine. This excretion will likely be highest during the first few days of keto adaptation (either in eating the keto diet or consuming exogenous ketones), but the body will retain more and the tissues will begin to preferentially burn the ketones as consumption continues. The liver is the major site of endogenous ketone production, so taking exogenous ketones (BHB Salts) would provide another source besides the liver to make ketones. Remember, exogenous ketones are a source of calories; so be sure to consider it in your daily goals. Exogenous ketone supplementation is not hard on the liver.