During the second episode of Game of Thrones' seventh season, we saw Samwell Tarly try to save Ser Jorah Mormont's life with an experimental treatment for his fatal skin disease, even though the Citadel's archmaester forbade it. So is Jorah cured of greyscale? Unsurprisingly, Sam did a very good thing.
In Episode 3, titled "The Queen's Justice," we see Archmaester Marwyn examining Jorah's healthy, bright pink (if a little raw) skin, and although the archmaester is probably quite surprised, he hides it well. After all, he barely listened when Sam asked about literature referencing possible treatments for greyscale, and he outrightly dismissed them as being even remotely useful in Jorah's very advanced case. In fact, Archmaester Marwyn's prognosis for Jorah was only six more months of mental acuity before he devolved into one of the zombie-esque Stone Men banished to Valyria. The disease itself would have taken years to do him in. So, Sam sneaks into his chamber in the middle of the night and follows the instructions in an old medical book, written by an archmaester who himself died of greyscale. After literally flaying Jorah of his diseased top layer of skin, Sam applied an ointment and hoped for the best.
As it turns out, the best is exactly what happened. They were forced to work in the dead of night and completely silently so that they wouldn't be found out. But Jorah's stifled screams paid off in the end. Archmaester Marwyn asks if he's in pain as he's recovering, but Jorah reports that it's not as bad as the greyscale itself.
He officially receives a clean bill of health when Marwyn declares that his infection is no longer active. Of course, the archmaester is suspicious about this miraculous healing, but Jorah dutifully covers for Sam. With an almost cheeky air, Jorah says that he simply started feeling better, attributing his good health to rest and the climate. Archmaester Marwyn is not amused, but he formally discharges Jorah from the care of the Citadel.
Sam does get a massive scolding, with good reason. He could have contracted greyscale himself, passed it to everyone he came into contact with, and, as Archmaester Marwyn puts it, "devastated the Citadel." But he didn't, and so he escapes punishment. He doesn't get out of his scut work either, though, and Sam immediately gets put back to work transcribing old scrolls. He's a tiny bit disappointed — he did save a life after all — but he is rewarded in that he hasn't been kicked out of his own personal Hogwarts for disobedience. As for Ser Jorah, he's on his way to reunite with Daenerys, having finally obeyed her order to cure himself.