You can earn free credits by inviting your friends to purchase credits.

You get 20% of the total number of credits they purchase. If your friend buys $50 worth of credits (500,000), then you get 100,000 credits for free. Additionally, your friend will also get 20% extra credits for their purchase (500,000 + 20% = 600,000 credits).

Click your referral link shown on the right-hand side and then send it to your friends.

As soon as someone purchases credits after visiting your referral link, your free credits will be given to your account. You will also be able to see these credits by going to your Keywords Everywhere's stats page, and then clicking "Credits".

Keywords Everywhere Referral Program 

Reference: Keywords Everywhere Referral Program