If after such hearing the commissioner determines that the seized property constitutes such unlawful property he shall declare such property forfeited and may, in his discretion, order that the seized property, in whole or in part, be sold, destroyed or retained for the use of hospitals, and state, county and municipal institutions and that the building or premises in or on which such unlawful property was located when seized shall not be occupied or used for any purpose whatsoever for such period, not exceeding one year, as shall be fixed by the commissioner.