How do keyword tool services get access to googles search data?

How do keyword tools like moz/longtail pro/semrush get all the search volumes?

I'd like to find a way to get the volumes for 100,000+ keywords myself without having to sign up for a new moz trial every day (they have 5,000 kw/month limit).

here: k-meta.com/domains_batch?domains=ebay.com,walmart.com,rei.com i use Lite that gives 10 000 keywords per day...