Suppose I'm granted a patent a month from now and it lasts for 20 years. This means that the patent bureau (such as USPTO) will have created a record which stores the patent claims and also the information about who the inventor is and who holds the protection rights.
Those 20 years pass and the patent no longer guarantees protection. What happens to the records in the patent bureau (such as USPTO)? Are they expected to be stored forever or are they discarded after some time?
Or suppose the maintenance fees are not paid (because the patent looks useless) and so protection is stopped earlier than in 20 years. What happens to the records?
How long are patent records stored and under which conditions they may be destroyed?