Mac and Windows
Download the new version and run the installer from the downloads page.
ZeroTier’s Linux install script
If you used ZeroTier's linux install script on the downloads page, it added the repo to your system. Use apt or yum to update zerotier-one.
For example, on debian/ubuntu based systems:
sudo apt update sudo apt install zerotier-one
Bonus tip: you can specify a version
sudo apt install zerotier-one=1.2.12
iOS and Android
Use the app store