When someone takes a 'vow of celibacy' (for whatever reason), does it have to be for life or temporary?

Ofcourse it would stop when you get married. Celibacy only applies when you don't wanna engage on premarital sex. That's all.

You can quit anything anytime you like..

i took a vow of celibacy just until 5pm

Depends on the person..

It's up to the person.

you can take it as an experiment , if it suits you , good if doesn't than you can quit it

Depends on the person and how long they're willing to commit to it. Also depends on their reasons.