Install Drush on shared hosting with SSH access?
you can also install manually as long as you have ssh access
# get drush latest 8 version
# drush 8 works with D8, D7 and D6
# https://github.com/drush-ops/drush/releases
wget https://github.com/drush-ops/drush/releases/download/8.4.2/drush.phar

# make it executable
chmod +x drush.phar;

# move it to home directory or any other directory
mv drush.phar ~/drush;

# go to that directory
cd ~

# find out the path to the directory
pwd
# the output would look similar to this
# /home/your_user

# edit the following file 
nano .bashrc
# or 
# nano .bash_profile

# add this the end of the file
alias drush='/home/your_user/drush';

# use the alias you just setup
source ~/.bashrc;