This root form (lemma) is used in 2 different forms in the NT: διατηροῦντες (PPA·NMP), διετήρει (IIA3··S).
It is glossed in 2 different ways: ‘was keeping’, ‘keeping’.
OET LUKE 2:51 Greek word=διετήρει (dietaʸrei) Morphology=IIA3··S English gloss=‘was keeping’ SR GNT LUKE 2:51 word 19
OET ACTS 15:29 Greek word=διατηροῦντες (diataʸrountes) Morphology=PPA·NMP English gloss=‘keeping’ SR GNT ACTS 15:29 word 22