TurboActivate.dat file changes at each download

Yes.

Thank you Wyatt.

Does this mean we have to always include the latest TurboActivate.dat we downloaded or can we use the previous ones as well (i.e. does downloading the latest invalidate previous TurboActive.dat files)?

Just download it once and use that in your app. We've made incremental improvements to the file format over the years, so it's best to use the latest version and discard old versions of the file. If you're using really old versions of the file you'll get an error when you use it in TurboActivate or TurboFloat.