Well, this is a great news for all publishers. From September 2016, Google has removed the limit of 3 ads per page. Now the publishers can place as many ads as they want.

This is a big deal for publishers, as by showing more ads they can increases the chances of more earning.

However, note that Google has set a criteria as well that must be met while placing more than 3 ads on one page. This is as follows:

1. The main criteria Google has set for placing more ads than three (old limit) is that the ads should not exceed your content. This means that the ads should not show too excessively that the content becomes inconspicuous, or the site looks like an ads-site mainly.

2. Pages should still follow their webmaster quality guidelines.

3. Rewriting, framing, mirroring content from other pages is not allowed.

4. Automatically generated content on which manual input e.g comment or review is not added is not allowed.

Google also stated that if a page has no or too little content, showing ads on that page may trigger Google to disable serving ads on that page.

This is obviously good for publishers as with more ads showing on their website, they can earn more, but at the same time, they have more responsibility of ensuring that the above-mentioned criteria is also met. So, before quickly moving on to place more ads on your site, make sure to ensure that your website meets the criteria, and if it does, start enjoying the freedom. Happy Adsensing! :) 

Google Reference: