Law & Order Legacies joins the ranks of Wallace & Gromit's Grand Adventures as another Telltale series that is no longer available for sale from digital storefronts. If you already purchased the game you should still be able to download the game from the digital storefront where you purchased it. Otherwise, there is no longer any way to purchase it digitally as the game has been removed from sale on Steam, the Telltale store, and iTunes.
Luckily, all hope is not lost, as like Wallace & Gromit's Grand Adventures, the PC version was released at retail, so it's still available while supplies last for people who still want it. However, unlike Wallace & Gromit's Grand Adventures, the retail version of Law & Order: Legacies was only available in the United Kingdom. So, outside of eBay, Amazon UK is your only chance to get it now.
Update: If you don't live in Europe, Amazon also has limited quantities available for only $3.
So, it might be worth picking up past Telltale games if you want them but don't already have them just in case. They are on sale now on Steam, so now's a good time to grab them.
Hector: Badge of Carnage, Puzzle Agent 2, and Poker Night 1 & 2 are the games that would be the most troublesome, as none of those were ever released at retail, so if Telltale loses the license to sell those, the ability to purchase them will be gone for good.
Law & Order Legacies is worth picking up at that price, in my opinion. The writing is quite dry, and it's a very casual adventure game (like a mix between Telltale's CSI games and Phoenix Wright, but without the humor), and the voice actors don't sound like the people they are playing (although their performances are good otherwise, so it might not be a problem if you're not a Law & Order superfan). However, it's really faithful to Law & Order, as you first play as a detective, searching for evidence and interrogating witnesses, and then play as a prosecutor using the evidence you collected to try to convict the accused. Plus, just like the show you are able to lose your case in court. Losing your case doesn't result in a game over, just a different outcome, which is actually pretty cool.
I reckon it's worth picking up for $3 though!