Mont. Code § 61-3-425
The license plates issued under 61-3-422 may be renewed as long as the amateur radio license is in force under the federal communications commission and the special license issued hereunder is in force. If the official amateur radio license is revoked or expires for any reason, the license plates must be removed immediately by the owner of the light vehicle or motor home, and the owner shall obtain standard license plates numbered as provided in 61-3-332. If the light vehicle or motor home is sold or otherwise transferred, the owner and holder of valid official amateur radio station and operator's licenses may transfer the amateur radio license plates to another light vehicle or motor home owned by the holder as provided in 61-3-335. On the revocation or expiration of the amateur radio station and operator's licenses, the license plates issued under 61-3-422 must be returned and surrendered to the department.
§ 61-3-425, MCA