Problem solved by support... If you have the same problem just:
I would suggest you to manually delete all keys from HKEY_CURRENT_USER\Software\Telerik registry.
To do so, follow these steps:
1. Open regedit.exe
2. Navigate to HKEY_CURRENT_USER\Software\Telerik
3. Delete the following keys (AccessToken, AccountMail, AccountToken and RefreshToken)
After that, run Telerik ControlPanel again and try to update it again.