I've installed php7 on my droplet but according to my phpinfo I still use php 5.59

Without knowing what distro you are using or how you upgraded to PHP 7, it is hard to give a thorough answer. Assuming you are on Ubuntu 14.04 and used the packages from the ondrej/php PPA, here are some things to check.

The way PHP is now packaged, you are able to co-install both PHP 5 and PHP 7. So it is possible to have both versions working with different applications.

If your PHP is being executed by Apache’s mod_php, first ensure that you have the package libapache2-mod-php7.0 installed on your system. Then, disable the PHP 5 version and enable the PHP 7 one:

sudo a2dismod php5
sudo a2enmod php7.0
sudo service apache2 restart

If Nginx is serving the PHP application using PHP-FPM, then ensure that the php7.0-fpm package is installed on your system. Then update your Nginx configuration’s fastcgi_pass directive from:

fastcgi_pass unix:/var/run/php5-fpm.sock

to

fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;

Remember to restart Nginx for the changes to take effect: sudo service nginx restart