Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
‡ mĕmŏrĭōsus, a, um, adj. [memoria], that has a good memory, Paul. ex Fest. p. 124 Müll.: memoriosus, et memoriose, Fronto de Differ. Voc. p. 2194 P.; cf.: memoriosus, μνημονικός, Gloss. Philox.
Hence, adj.: mĕmŏrĭōse, with a good memory, Fronto l. l.