The first commercially-produced time machine was a disaster. The sixth person to buy one immediately used it to go back in time and give it to herself so that she didn't have to buy it in the first place, and this started a trend.
At first the company which had manufactured the time machine was quite surprised to find themselves having never been in business due to lack of consumer interest. But soon enough one of the company execs, near insanity from being hounded by creditors over his several billion dollars of personal debt, murdered the second purchaser after ending up (quite by chance) seated at the table next to him in a charming little cafe on Mexico 4. He then used the man's time machine to chronologically stalk all company employees and each of the original customers in an effort to uncover what had happened – he got lucky and only had to follow 38 people around (over a total of 2,707 subjective years) to become witness to the fraudulent exchange before going back to the future to share what had happened and leave himself a note not to kill that guy.
Retroactively forewarned, the company founders went back and re-founded the company, this time telling their PR firm to go for a broad-based appeal; to exhort everyone to start saving up now for the time machine they'd be able to buy in the future, instead of the earlier approach they were about to try of marketing to the wealthy few who could afford an early production model. It was a much easier sell now that they knew exactly when they'd make it to market.
It worked, and the newly-created temporal security engineering team came up with a perfect solution to the self-theiving problem: the time machines would be keyed to their owner's RNA at time-of-purchase. Cellular aging analysis would prevent anyone other than the owner – and more importantly, younger versions of the owner themselves – from using the time machines.
Sadly, as a result of this somewhat hastily implemented improvement, fewer people than anticipated ended up buying time machines. It turned out that they didn't like artificial limitations placed on on when they could use something they had paid for, and some particularly unreasonable people even complained about having to turn over a complete genomic sequence to a private company just to buy an appliance.
And then, when someone figured out that they could use engineered stem cells to incubate tissue samples of themselves and hand those over along with the time machine, it all happened again.
Undeterred (and this time prepared (again)), the once-and-future board of directors, simultaneously furious at the loss of stock grant bonuses and filled with glee in anticipation of them, decided to try again. Using a fleet of time machines and a cadre of employees set aside for just this purpose, they replayed the actions of the insane exec from the first iteration of the company. In the twinkling of an eye, the problem was solved, the board was flush with wealth, the accounting department sent a memo stating that the operation had taken just short of 43 million man-years at a cost of 7.2 quadrillion dollars (but that they were still comfortably in the black), and the company promptly went out of business again.
Some lone miscreant had spent several lifetimes in a loop of researching the time machine's system encryption and handing his notes and time machine off to his younger self before successfully figuring out how to bypass the biometrics subsystem altogether. Once that info made it onto the cyberwebs, the game was over.
Meanwhile, back in the now-thenfuture, the company began lobbying Hypercongress to make chronologically retrograde gifting of time-traversal devices illegal. They passionately argued that they had just lost dozens of millions of quintrillions of dollars in time, investment, and personal fortunes (three times in a row); to say nothing of all the sales they weren't just about to make; and that it was all going to happen again, any minute now, some weeks ago (the hearings had dragged on a bit).
The lobbying paid off, of course, because the time machine industry was (just about to become) a major sector of the overall economy. Staggering fines were put in place, press conferences were held, and schoolchildren in the past were educated about the wrongness of stealing the time machines they'd be able to buy in a few decades.
Sadly, some people just will not obey the rules, and the whole cycle repeated itself before anyone had a chance to really even notice. Outraged (and unenriched) politicians pledged their utmost support to the time machine industry. Even stiffer fines were enacted. Fraudulent use of time machines was criminalized, with penalties in the most severe cases including retroactive wage garnishment, from-birth imprisonment, and the ancestral death penalty. Police and even troops were sent back in time to find, arrest, and/or eliminate offenders, Education initiatives were pushed back to the generation before the one which would actually be able to buy time machines. Plans were made to build a giant computer in the distant past – using the most modern technology – to enable officials to sift through, store, and analyze all civilian communications for evidence of time machine theft.
Just as (surely) final victory seemed within reach, the warp and weft of spacetime visibly shifted. A researcher from 1,500 years into the future had built a clean-room implementation of the time machine from a combination of his own research and the mostly-forgotten (but recently expired) patents. He had then gone back in time and filed a patent of his own over two thousand years before the then-present, causing the intellectual property of the original time machine company to be invalidated on the grounds of prior art. The battle was over.
Unless, just perhaps, they could have patents from persons not yet born declared invalid...