No, your employer never has to give you a raise, or a promotion. Unless you belong to a union, which provides many job protections, or you have a written contract that guarantees you a set time period for employment and, for example, requires "good cause" to fire you, then you're "at will," meaning you can quit whenever you want to, and you can be fired at any time without notice for any reason or no reason, and you're not entitled to any severance pay. Since your employer can fire you whenever they want, they can also do less than fire you, like reduce your hours and/or salary.
The fact that you're well-liked and do great work and have been there 7 years may only be keeping you employed. However, long term employment can sometimes cause a change in status from "at will" to "good cause" employment if your employer has made representations about job security, needing good cause to fire you, etc.
Your employer does have a few limitations. Some of the main ones are that they have to follow their own employment policies, they can't discriminate against you because of your gender, religion, age, race, national originm etc., and if they fire you for being a "whistle blower," that's wrongful termination.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.