How long can this product be used?

Depends how much you use it, but it could last up to 2 months in my opinion. Maybe more time if it's used less frequently.

Does this remove cigarette smell?

If you absolutely can not machine wash or use the extension of a rented carpet cleaner (for upholstery) this may be your best bet. It is a POWERFUL smell. Be cautious if anyone has a sensitivity issue. You do not need to use a lot.

how long does it last?

It lasts long but the manufacturer does not specify the duration however, customers has various views based on experience ranging from 1 day to a week ... this statement is totally based on individual usage and experience ... may vary from case to case ... but it will surely give you refreshing fragrance ...