Is it OK to use cleaners such as liquid plummer,draino plumbing snake.etc every now and then to keep sewer line clear from house to street.my line did get clogged with paper and the plumber flushed with water hose to clear.apparently during the cold spell,water in the ground line to street froze and caused a blockage.

Your sewer line should have no standing water in it at any time. If it does, than you have different problem. You may have roots in the pipe creating "barriers" that prevent water from draining or you may have "low spot" somewhere in the line.

You should have video inspection done first to see for yourself what is preventing water from draining. Based on the inspection, proceed with repair.