Two weeks before your subscription expires - they auto-renew if you didn't disable that function. I didn't disable the goddamned function and - of course - they auto-renewed me for the Cadillac plan that's $160 a year. My perfectly fine cheapie plan was $60.
I'm in the process of trying to get a refund and I'm not enjoying it.
I know Private Internet Access does this too. Key is like Amazon, Walmart, etc subs when you're broke, kill the subscription soon as you sign up.