Patents once they run their course, then go into the public domain. I beleive the term for design patents (USA only) is 14 years and utility patents (USA only) is 20 years. The duration terms in other jurisdictions can vary somewhat. Note that a Provisionally filed patent can be filed for a period of 12 months and extended a further 6 months to 18 months in total; after which a national or PCT patent application programme can be embarked upon.