The term goes back to the American whistleblower Edward Snowden. He often says goodbye with "stay free" instead of "stay safe". He explains that an excessive desire for security always comes at the expense of freedom. He wants to increase the value of freedom by using this closing phrase. Other people use this enactment to express their loyalty with Snowden's values.
A: Ok, see you. Stay safe!
B: Stay free, brother!
A common expression in parts of Australia to motivate someone (Example 1).
The expression is also used as a compliment for good performance (Example 2).
The origin of the expression is a campaign by Responsible Wagering Australia (RWA) to encourage people to set a deposit limit as part of a more responsible approach to betting and gambling.
Example 1:
A: I can't concentrate, I lack motivation.
B: Come on, set a deposit limit!
Example 2:
A: I came first in the table tennis tournament.
B: Oh wow, you definitely set a deposit limit!