The DB-IP free database is a subset of the full database with reduced accuracy.
The free IP-to-city database by DB-IP is licensed under a Creative Commons Attribution 4.0 International License.
You are free to use this database in your application, provided you give attribution to DB-IP.com for the data.
In the case of a web application, you must include a link back to DB-IP.com on pages that display or use results from the database. You may do it by pasting the HTML code snippet below into your code :
<a href='https://db-ip.com'>IP Geolocation by DB-IP</a>