The article examines the transformation of the legal regime for apartments in the context of the expansion of their use for permanent residence of citizens, while formally retaining the status of non-residential premises. It investigates the functional approach to assessing the suitability of premises for living and its impact on overcoming the strict dichotomy of 'residential/non-residential' in Russian law. The conclusions of the Constitutional Court of the Russian Federation, formulated in Resolution No. 4-P dated 03.02.2026, regarding registration at the place of residence in apartments and the associated constitutional and legal consequences, are analyzed. It is concluded that a new comprehensive legal institution of non-residential premises suitable for living is being formed, and proposals are made to clarify housing, civil, and procedural legislation.