Hi,
yes, you need to buy another license of Rebex Buru SFTP Server for the second machine too.
Rebex Buru SFTP Server is licensed on per machine basis. This means that you have to get a valid license for every machine on which you run the SFTP Server.
For more information please see our Frequently Asked Questions, section Licensing:
https://www.rebex.net/buru-sftp-server/doc/faq
Please contact us on: sales@rebex.net if you need to discuss anything regarding your purchase.
Thank you!