In Professional edition you can verify emails in Direct Mode, via Socks servers and Web script. Also can use List Tools and External Datasourses.

Here you can read help - Manual, see video, how use program - Video Tutorials and download free version - Download

You pay one time for lifetime key for one PC and unlimited emails. Also you have free support and update of program in current version.

Limit of verification on 1 Socks server - 20000 emails in day. You get Socks settings (IP address, port, username and password) of server. You can verify 600 000 emails in month.