Let $G$ be a graph of order $ n(G) $, local metric dimension $ \dim_l(G) $, and clique number $ ω(G) $. It has been conjectured that if $ n(G) \geq ω(G) + 1 \geq 4 $, then $ \dim_l(G) \leq \left( \frac{ω(G) - 2}{ω(G) - 1} \right) n(G) $. In this paper the conjecture is confirmed for the case $ ω(G) = 3 $. Consequently, a problem regarding the local metric dimension of planar graphs is also resolved.