Keep is the present tense. We use keep and a gerund verb form to express the idea of repeated or continual action.
Simple Past
The sun kept shining
He kept being late
I kept knocking on his door until he answered
Simple Present
I keep seeing John
The car keeps stopping
The dog keeps barking
Simple Future
I will keep writing until I hear from him.
The alarm will keep ringing until you turn it off
The fire will keep burning until all the wood is used up.