To be eligible for matched content feature, your website should meet some requirements put forth by Google. These requirements pertain to traffic, number of unique pages and other conditions.
To check whether your site is approved for the feature, follow these steps -
1. Sign in to your AdSense account.
2. Click on GEAR icon and select Settings .
3. Under Account , click on Site Management .
4. Look for the Matched Content column under Owned tab. Status of your eligibility will be shown either as Approved or Not Approved .