Generally speaking, Purple DS apps supports t he load  two major releases  of the different app platforms.

iOS apps

For now, Purple DS supports iOS 9, 10 and 11. But the support for iOS 9 might end in near future. Information on i OS 9/10/11 can be found   here   .

Android Apps

Currently, Purple DS apps support Android 4.4 up to the latest Android release. 
Kindle Purple DS apps are available on Kindle Fire.

The   decision to discontinue support for Purple DS is based on the distribution of the OS version.  Please see the distribution here for iOS  and here for Android .  

Purple DS Composer   supports MAC OS Mountain Lion to Sierra.

Purple DS Plugins   for Adobe® InDesign® is available for CS6 / CC and CC2015 / CC2018.