A pure devotee, whose mind is always engaged in the service of the Lord, can certainly appreciate the impermanence of this material world. Although such a devotee may be engaged in executing material activities, this stage is called anāsakti. As explained by Śrīla Rūpa Gosvāmī, anāsaktasya viṣayān yathārham upayuñjataḥ. A devotee is always unattached to material activities because in the liberated stage his mind is always fixed on the lotus feet of the Lord.
This material world is called dvaita, the world of duality. A devotee knows very well that everything within this material world is but a manifestation of the Supreme Lord's energy. To maintain the three modes of material nature, the Supreme Lord takes on different forms as Lord Brahmā, Lord Viṣṇu and Lord Śiva. Unaffected by the modes of material nature, the Lord takes on different forms to create, maintain and annihilate this cosmic manifestation. The conclusion is that although the pure devotee appears to engage in material activities in the service of the Lord, he knows very well that material enjoyment for sense gratification has no use whatsoever.