More than £25,000 of public money has been spent giving Martin Ramsay, 38, methadone since he was 16 in 1991.
Despite being on a massive daily dose of methadone, Ramsay has continued to use heroin and has almost 60 criminal convictions.
His extraordinary abuse of the methadone programme came to light when he admitted his latest opportunistic theft to fund his heroin habit.
He appeared at Perth Sheriff Court and admitted stealing three silver rings from The Loft cafe, Perth, on December 18 last year.
Solicitor Jamie Baxter, defending, said: "This man has had a long-standing drug problem for 25 years. He had relapsed at the time of this offence.
"He is presently on a methadone script and receives counselling. He has been participating with the Perth drug clinic. His methadone script is currently at 100 mls."
Mr Baxter told the court that Ramsay, from Iona Court, Perth, had repaid the value of the rings and wanted a chance to prove he could behave in the community.
Sentence was deferred until next month.
Ramsay's long-term use of methadone was first revealed nearly five years ago, when it provoked outrage from politicians.
At that stage Ramsay - who once committed 50 crimes in a single year - had his situation described as "incredible" by his own solicitor.
Following Ramsay's court appearance yesterday, local MSP Roseanna Cunningham said: "This man's case is a sad reflection on the cost to society of drug addiction and the extent to which heroin blights the lives of users and all of those around them.
"A variety of measures have been introduced in recent years, but we need to continue to explore ways of breaking the cycle of drug misuse and offending."
A report by the Government-backed Scottish Drugs Strategy Delivery Commission in August called for a review of the £36 million annual methadone programme.
Jackson Carlaw, health spokesman for the Scottish Conservatives, called the Scottish Government's drugs strategy defeatist and said: "We will simply continue parking people on alternatives with no hope of them getting their lives back on track.
"A tougher approach on this matter would help everyone, from addicts and their families, to the victims of the crime. Many regard the Scottish Government's rhetoric on this issue as one of defeat."
Official figures show that of the 438 drug deaths in Scotland in 2011, methadone was the most commonly implicated drug, involved in 234 cases.
David Liddell, director of the Scottish Drugs Forum, acknowledged that 22 years was a particularly long time to be on methadone, but said that for some users long-term use was the most appropriate treatment.
He said: "There are about 24,000 people on methadone in Scotland at any one time out of about 60,000 problem drug users. There is a group, around a third, that are long-term users but for some this is the most appropriate treatment.
"For many, methadone will have kept them alive and in contact with services. The majority of addicts die in a time when they have come off methadone for whatever reason and lost that contact.
"They have to come off when they are ready and the underlying issues have been tackled. For that reason, setting arbitrary timescales is not helpful."