PLBs have no subscription. You must register them with the government but it's free. And mine only cost $250--watch prices on Amazon to get a better deal.
What you are thinking of are the SPOT & inReach units--those have subscription fees but provide you text messaging while off the grid. PLBs are single-shot HELP messages, they can't be customized. (Are you simply stranded like these guys, non-threatening injury that keeps you from getting yourself out, or is it a major issue--say, the guy here last year that keeled over on top of Hell Hill. It probably wouldn't have made a difference but the hour it took to get help certainly wasn't good.)
What you are thinking of are the SPOT & inReach units--those have subscription fees but provide you text messaging while off the grid. PLBs are single-shot HELP messages, they can't be customized. (Are you simply stranded like these guys, non-threatening injury that keeps you from getting yourself out, or is it a major issue--say, the guy here last year that keeled over on top of Hell Hill. It probably wouldn't have made a difference but the hour it took to get help certainly wasn't good.)