A ticket of leave was a document of parole issued to convicts who had shown they could now be trusted with some freedoms. Originally the ticket was issued in Britain and later adopted by the United States, Canada and Ireland.
The ticket system was first introduced by Governor Philip Gidley King in 1801. It officially began in 1853 when prisoners transported from the United Kingdom to Australia, and subsequently other colonies, who had served a period of probation—and shown by their good behaviour that they could be allowed certain freedoms—were awarded the ticket of leave. Once granted, a convict was permitted to seek employment within a specified district, but could not leave the district without the permission of the government or the district's resident magistrate. Each change of employer or district was recorded on the ticket. 
Originally the ticket of leave was given without any relation to the period of the sentence being served. Starting in 1811, a concept of serving some term in prison first was established; and in 1821 specific terms were added to the length of the prisoners sentence that must be first served before a ticket was to be allowed. These were 4 years served for a 7 year sentence, 6 years of a 14 year sentence, with a life sentence meaning that 8 years must be served before the "ticket" could be considered.
Ticket-of-leave men were permitted to marry, or to bring their families from Britain, and to acquire property, but they were not permitted to carry firearms or board a ship. They were often required to repay the cost of their passage to the colony.
A convict who observed the conditions of his ticket-of-leave until the completion of one half of his sentence was entitled to a conditional pardon, which removed all restrictions except the right to leave the colony. Convicts who did not observe the conditions of their ticket could be arrested without warrant, tried without recourse to the Supreme Court, and would forfeit their property.
The ticket of leave had to be renewed annually, and those with one had to attend muster and church services.
The ticket itself was a highly detailed document, listing the place and year the convict was tried, the name of the ship in which he or she was transported, and the length of the sentence. There was also a detailed physical description of the convict, along with year of birth, former occupation and "native place".
In the Second World War the "ticket of leave" was a colloquial name given to the papers allowing a soldier to take leave from active service.