It is worth looking at what chess.com say on the subject.
First, regarding free membership:
First of all, if you hold a qualifying title (see list below), you get a lifetime Diamond membership for free. That gives you access to the best features available online for playing, sharpening your game, or finding students & doing online coaching!
- GM - Grandmaster
- WGM - Woman Grandmaster
- IM - International Master
- WIM - Woman International Master
- FM - FIDE Master
- NM - National Master
- CM - FIDE Candidate Master
- WFM - Woman FIDE Master
- WCM - Woman FIDE Candidate Master
Next we should look at chess.com's definition of the national master title to see who is eligible for free membership like this:
What Is The National Master Title?
The national master title (abbreviated as NM) is a special title, as it is not recognized by the International Chess Federation. As the title suggests, it is a master title that is awarded by national federations.
Not every chess federation awards this title, but several large federations do. In general, federations that award the NM title do so to players who achieve a national rating of 2200—although there are exceptions as well, which are discussed below.
So, basically chess.com are recognizing all NM titles awarded by federations. They are trusting the individual federations not to devalue their titles.
Can such a federation lower their NM title requirements thereby giving their players free chess.com membership?
Would chess.com care if that happened?
Since the original decision to award free lifetime membership to titled players was a business decision it entirely depends how such a move would affect their business. If they see that it is positive for their business then they will welcome it. If it is negative then they will change the rule.