2020 Mathematics Subject Classification. Primary: 35K57, 35B40, 35B41; Secondary: 45K05. Key words and phrases. Nonclassical diffusion equation, the time-dependent pullback global attractors, memory, lacking instantaneous damping. The research is financially supported by National Natural Science Foundation of China (Nos. 11101053, 71471020). ∗ Corresponding author: Jiangwei Zhang.