These provisions shall apply to all buildings or structures or use of a building or structure or lot lawfully existing prior to the effective date of the original zoning law, or of subsequent amendments, revisions or reenactments of such law, which do not conform to the provisions of said original zoning law, or such revisions or reenactments on their effective dates.

Each business or industrial use which under this chapter or any amendments thereto requires a special use permit and which use was in existence on the date of the enactment of this chapter or amendments thereto must file with the Planning Board a certificate of substantial compliance with this chapter or any amendments thereto within one year from the enactment of this chapter or any amendments thereto. The user shall thereafter continue such use in the manner permitted by the Planning Board. Failure to file the certificate of substantial compliance in the manner prescribed above shall deem the use discontinued.