Identity Verification Code Prompt Appears on Every Salesforce Login

Browser privacy settings to save cookies for Salesforce sites 

Note: Before making any changes in your browser, verify with your IT department that the changes comply with your security policies.

At the admin or end-user level, edit your privacy settings:

Google Chrome

1. Click Settings.
2. From Privacy and Security, navigate to Site Settings | Cookies and site data
3. Go to 'Sites that can always use cookies' section, click Add then enter: [*.]salesforce.com
4. Click Add.
    

Optional: Set trusted IP ranges for your organization 

Specify a range of IP addresses on a user’s profile so that users can log in without being prompted to verify their identity.

For detailed instructions, read Set Trusted IP Ranges for Your Organization.