Keep is an irregular lexical verb; it has the third person form "keeps" (/ˈki:ps/), the -ing form "keeping" (/ˈki:pɪŋ(g)/), but an irregular preterite and past participle "kept" (/ˈkept/). The last may be over-regularised to *"keeped" (*/ˈki:pt/).
Keep catenates with a gerund, i.e. "keep doing something".
Keep has some multi-word verbs, namely:
- keep at
- keep away
- keep back
- keep down
- keep off
- keep on