1) Assist 2) Be helpful or useful 3) Help 4) To assist in carrying out 5) To be useful to 6) To serve as a subordinate 7) To serve to promote 
to be useful to; to promote
• (v. t.) To serve in subordination or instrumentally; to be subservient to; to help forward; to promote. • (v. i.) To be subservient or subordinate; to serve in an inferior capacity.
Sub·serve' intransitive verb To be subservient or subordinate; to serve in an inferior capacity. « Not made to rule, But to subserve where wisdom bears command.» Milton. Sub·serve' transitive verb [ imperfect & past participle Subserved ; present participle & verbal noun Subserving .] [ Latin subservire ; sub under + servire to serve. See Serve .] To serve in subordination o...
[v] - be helpful or useful
to be useful or instrumental in promoting (a purpose, action, etc.): Light exercise subserves digestion. · to serve as a subordinate.