A World of Tanks demo account is a temporary account that is created automatically when you enter the game for the first time. It allows you to play without registering.
Before creating a demo account, you need to read and accept the EULA and Privacy Policy in the Wargaming Game Center.
A nickname for a demo account is created automatically and cannot be changed without linking to the Wargaming.net ID system.
A demo account gives you access to the tutorial mission only. To unlock all the game features, complete the registration while authorized via the demo account. After that, you will be able to enter the game using your login and password.
If you reinstall the Wargaming Game Center or do not log in to your demo account for 30 days, it will be automatically deleted.