In order not to exceed the monthly traffic limit of your virtual server, you can install the following application on your server and limit your network speed.
Install into Ubuntu, Debian with the command:
sudo apt install wondershaper
Install into CentOS with the command:
sudo yum install wondershaper
sudo ifconfig -a
ip a
You can see the set limits as follows:
sudo wondershaper eth0
An example of setting a limit in kilobits/s, for example, for downloading 20 Mbps, and for sending 5 Mbps:
sudo wondershaper -a eth0 -d 20000 -u 5000
Or so (depending on the version of wondershaper):
sudo wondershaper eth0 20000 5000