During the early days of MMORPGs, a game that required a monthly subscription fee was a new idea that nobody thought would work. It was World of Warcraft that broke that tradition, making the concept work with great success, and other games have tried to copy their model but haven't enjoyed the same popularity.
The subscription-based MMOs without a free-to-play version are few and far between these days, and many that tried reverted to free-to-play mode. Often, it was because the marketing department had decided that in-game monetization was more lucrative. Most of the time it only took a few months before a free version was released or the whole game changed over completely.
6 Rift
Rift was launched in March 2011 as part of the WoW-killer trend, and given that it had a similar aesthetic and was also a fantasy-based MMO, it seemed to have a good chance. The game has retained its popularity and still exists, but someone saw the potential in a free version, and Rift Lite launched in the spring of 2012.
This was a free version of the game that ran alongside the subbed version and changed once the player reached level 20. The game went completely free-to-play in June 2013 and still retains this status, but the option is available for extra perks and rewards for Patrons, who pay a monthly fee.
5 Wildstar
It was an ambitious project that blended the genres of fantasy and science fiction into a single game, including the lore and storytelling that made other games successful. The game was released on June 3, 2014, and the price to play included a monthly subscription fee.
The game got mostly positive reviews for design and combat, but some negative ones for the generic storyline. Despite the positive reception, it continued to lose players and changed to free-to-play on September 2015 with the introduction of some other design features. It wasn't enough to save the game from its ultimate fate, however, and the underpopulated servers went offline permanently in November 2018.
4 Dungeons & Dragons Online
Of course, the vast library of Dungeons & Dragons media would include an MMO game. It was initially launched in 2006 and required a subscription fee, but after two years the game had less than 100,000 subscribers. That's partly why the Eberon expansion of 2009 also included a free-to-play version.
Ownership of the property changed in 2016 when Standing Stone Games took over but promised to continue its development. The game continues to this day with the same payment structure as 2009, with paying and free-to-play gamers side by side on the D&D servers.
3 Star Wars: The Old Republic
No other MMO in this era was released with the same level of expectation as Star Wars: The Old Republic. It was poised to take over the MMO world, and the fanbase that was dedicated to the IP was part of the clout the game brought with it. LucasArts launched the game in December 2011 after all kinds of hype and fanfare that included a very exclusive open beta.
The game didn't live up to the hype, to put it mildly. Massive zones seemed unfinished and the space combat was simple rail games. SWTOR went free-to-play less than a year later in 2012 and is notorious for the number of in-game micro-transactions currently available.
2 DC Universe Online
The timeline of the development of the DC Universe Online is a convoluted one, with the game being released on several different platforms at a variety of different times. The only version that included a subscription was the earliest launch for the PlayStation 3 and Windows in January 2011.
The game went free-to-play, with the addition of a variety of microtransactions, in November of the same year that it was released. Versions of the game for the PlayStation 4, Xbox One, and Nintendo Switch followed, and all of them continue in the free-to-play model.
1 The Lord Of The Rings
One of the few other games with an IP to match big titles like SWTOR, The Lord of the Rings was a subscription-based game when it was first released in 2007. It had a good run of three years and several expansions, some of which were free but others that required a one-time payment, until it went free-to-play in 2010.
The ownership changed from Warner Bros. to Daybreak Game Company in 2016 and continues to thrive and develop. The game is still going strong, as one would expect because of the popularity of the subject matter.