The only updates you wouldn't be covered for are hardware updates and they don't happen that often.
I bought an early version of Airbox Clarity and have had all software updates for free ever since. The Aware Navigation software is made by Airbox and based on the same software as Clarity.
If you want navigation you should also consider Clarity. I believe Aware with Nav is the same as Clarity, but Clarity's hardware is a bit more powerful.