You need to purchase the Email Verifier credits based on your needs. 

Following is the tiered pricing for email verification. If the email status is unknown then it is not calculated against the credit.

Email Verify CreditsPrice
1K credits$7.99
5K credits$39.99
10K credits$49.99
25K credits$124.99
50k credits$249.99
75k credits$324.99
100K credits$399.99
250K credits$749.99
500K credits$1,099.99
750K credits$1,324.99
1M credits$1,549.99