You are most likely to get DTS Sound Unbound for free if you own:
There is no fully "free license" for commercial use. dts sound unbound free license free
For a regular user, the app and the basic features are generally free to try or free to use if your hardware already supports it. However, unlocking the full DTS Headphone:X or DTS:X features usually requires a payment or specific licensed hardware. You are most likely to get DTS Sound
Before you pay for anything, do this: