There are many ways to make money off of your game, even while it is a work in progress. Whether this money goes towards further developing your MMORPG or to paying off your living expenses, there is money to be made from your work.

Membership Service
A common practice amongst commercial online games is to offer a subscription or "membership" service. If a player subscribes to your game, they pay a nominal fee to you each month. This fee may allow the subscriber access to extra content, such as new quests, items and zones, or it may be a requirement just to play your MMORPG. A good design is to allow your free users access to a portion of your game, which acts as a trial, and subscribers access to the full world.

Cash Shop
Cash Shops work around the premise of players purchasing in-game items for real money. The option to buy game items for real money is sometimes criticized by MMORPG players, especially when the items offer extra power to the player purchasing them. However, MMORPG's which attract an audience of paying players are likely to be more profitable than a membership service. Some games that run cash shops offer only aesthetic items, which generally is accepted as fair practice. Developers are able to sell pretty much anything, from pets and houses to XP multipliers and respawn tickets - anything is a viable profit source.

Donations
Donations are more likely to produce funds when an MMORPG has no other commercialization attached to it. Strong community support and developer interaction can assist with producing donations. Some indie game developers make upwards of $6000 per month from donations alone, and it's very easy to setup.

Advertising
Advertising can be used in-game or on your game's website. Google AdSense is the most common advertising service, but unfortunately doesn't allow for advertising within games at the moment. The service earns you funds whenever an ad on your site is clicked, while Project Wonderful is a view-based advertising service which can be used for in-game advertising, but earnings are likely to be less. You can also directly approach various companies that might be interested in advertising in your game. A common placement for in-game ads is at the start or end of your game, as ads displayed during the gameplay itself are often considered distracting or invasive.