It is available as shareware, with a free trial or demo version that you can download. However, be aware that some "cracked" versions available online are often malware, so it is best to obtain it from a trusted developer source if possible.
Windows 10 blocks unsigned drivers by default. The KX-TES824 USB driver is unsigned. panasonic kxtes824 software windows 10 download better free
Drivers originally designed for Windows 7 (32/64-bit) typically work on Windows 10. It is available as shareware, with a free