From Drupal 7 or Drupal 8, follow the instructions below on how to verify a site for Google:
Click here to visit Drupal's documentation
Step 1
Get your verification code provided from Kliken. It should look something like the content below
<meta name="google-site-verification" content="SOMESTRINGGOESHERE" />
The important part is the value of the "content" attribute, so remove the rest of the string so it looks like the following:
SOMESTRINGGOESHERE
Step 2
Make sure the Metatag: Verification module is enabled, it comes with the main Metatag module.
Step 3
On admin menu go to Configuration > Search and Metadata > Metatag
Across from the Global item, open the Override or Edit link, as is appropriate.
Click to expand the Site Verification section (underneath Advanced).
Copy and paste the verification key from step 1 into the "Google" field.
Click the Save button.
Step 4
The metatag should be added to all pages and should look like this
<meta name="google-site-verification" content="SOMESTRINGGOESHERE" />