The free version adds a QR code watermark to videos that require conversion or aggregation. A license key removes this completely.
After payment, the license key is sent to your provided email address. If you lose it, you can use the License Recovery tool Register the License Open Firefox and go to the Add-on settings for Video DownloadHelper. Select the Register an existing license Copy and paste your key into the field and press Google Groups Key License Features One-Time Payment video downloadhelper firefox license key
Yes, your license key can be used on all your devices for the same browser type (e.g., a Firefox license works on both Windows and Mac Firefox). The free version adds a QR code watermark