Your account will be charged for each request.
The cost can be calculated on the Pricing page.
Top Google Searches (Legacy)
Note that the structure of DataForSEO Labs API requests and responses was updated on 2022-03-19. However, we will continue supporting the legacy version documented here. You can review the documentation of the new version by this link.
 
The Top Google Searches endpoint of DataForSEO Labs API can provide you with over 3.5 billion keywords from the DataForSEO Keyword Database. Each keyword in the API response is provided with a set of relevant keyword metrics, including AdWords and Bing Ads metrics, product categories, and Google SERP data.   
The working mechanism of this endpoint is different from others. To get over 1000 keywords, you will need to make several consecutive requests with the first one containing all the necessary parameters for making a request, such as limit, language and location codes. By specifying the unique offset_token received in the response to the first request, you will be able to get another batch of up to 1000 keywords along with another offset_token. By leveraging this system of consecutive requests, you can gradually dump all the data you need from our keyword database.