To install memached on server running Debian and plesk Onyx do the following:
apt install plesk-php71-dev gcc make git pkg-config zlib1g-dev libmemcached11 libmemcached-dev git clone https://github.com/php-memcached-dev/php-memcached.git cd php-memcached/ git checkout php7 /opt/plesk/php/7.1/bin/phpize ./configure --disable-memcached-sasl --with-php-config=/opt/plesk/php/7.1/bin/php-config make && make install echo "extension=memcached.so" > /opt/plesk/php/7.1/etc/php.d/memcached.ini plesk bin php_handler --reread