You can use your invite code only once while creating your World of Tanks account.
If you already have an account with World of Tanks, share your invite code with a friend!
Instruction for Invite code
1. Click Create Account: enter your email, desired in-game name, and password.
2. Click “Have an invite code?”
3. Submit your invite code.
4. Click Play for Free.
5. Complete your registration with World of Tanks, then install and run the game. Enjoy!