According to our agreement, one Web Server License cannot be deployed to multi machines at the same time.
If your test server keeps one copy of the web application for further development/test along with the production server, your test server requires one license, and the cost is 50% off the regular Web Server License. Please contact sales@dynamsoft.com for the reimbursement.
Otherwise, your test server requires no license. You can simply remove all Dynamic Web TWAIN related files from your test server and put them on the production server.