maintains
main-tains
verb
States firmly that something is true, often despite disagreement or evidence.
"She maintains her innocence in court."
verb
Keeps something in good working order or condition through regular care.
"He maintains his classic car meticulously."
verb
Causes or enables a condition or state to continue; keeps at a certain level.
"The firm maintains high quality standards."
Thesaurus
Synonyms: defend, keep, observe, preserve, keep up, conserve, uphold, exert, wield, asseverate, assert, sustain