A memory device and associated control method are provided. The memory device includes a memory array and a control circuit, which are electrically connected with each other. The memory array includes a plurality of memory groups. A first memory group among the plurality of memory groups includes at least one first memory unit. The control circuit executes the control method including following steps. Firstly, a first timestamp corresponding to a first time point is recorded when one of the at least one first memory unit is programmed. Then, state of the first memory group is identified based on the first timestamp and an identification rule, and the first memory group is retired when a condition being predefined in the identification rule is satisfied.