Md. Code, Real Property § 14–903

A service agreement, or any part of a service agreement, may not:

(1) Be effective for more than 1 year; or

(2) (i) Purport to run with the land or bind subsequent bona fide purchasers;

(ii) Purport to create a lien, encumbrance, or security interest on the residential property of a party to the service agreement; or

(iii) Allow the service provider to assign or transfer the right to provide services under the service agreement to another person without notice or the consent of a party to the service agreement.