Ok, so at the end of the Limitess Film, it's true that it appears that Morra was not off NZT and has chosen the path of politician for an undisclosed reason that ultimately sets up the depate of his motives in the sequel TV show, which are not clear and muddied by Agent Sands and the Legion of Whom...
But the idea of a "tweaked NZT" was mentioned in some of the final lines of dialogue between Eddie Morra and Carl Van Loon:
Carl Van Loon: What are you doing? Do you wanna be president of the United States or brain dead, stuck full of tubes?
Eddie Morra: I’ll take my chances.
Carl Van Loon: I told you, your chances don’t exist. We shut down your lab.
Eddie Morra: You don’t think some smart ass in NZT might have two or three or even four labs?
Carl Van Loon: So what? You’re not making anymore.
Eddie Morra: That’s right. I’m not. I thought better of it. See, once you know what’s in it, you can tweak and re-engineer it, and get
the bugs out. Taper off. I’m off it, Carl.
Carl Van Loon: Well, on it or off it, there’s no scenario where you’re not working for me.
Eddie Morra: How are you gonna pay me? In cigarettes?
So bassically, just like he was lying about being off NZT, it's more that Morra didn't tell Van Loon the entire truth and becomes "an unreliable narrator", because in Limitless TV series, despite Morra's manipulation of Brian Finch, the truth is, Morra, as he confesses to Brian in the Pilot, was most likely still having side effects in between the film and the Tv series. The time between them is four years and Morra says he had a headache two years ago.
Limitless 1.01 Pilot - Transcript:
Eddie Morra: You think it's bad now, it's only gonna get worse. You actually might remember this moment as the last time you felt
vaguely human. But it doesn't have to be that way, Brian. I took a
pill this morning. I've taken a pill every morning for the past four
years. I can't remember the last time I felt bad. That's not true. No,
I had a headache two years ago.
Biran Finch: How how did you how did you do that?
Morra: That. Millions of dollars of private research. It works on a cyclical enzyme system. Oh, you don't know what that means. It
doesn't matter. All you need to remember is that every so often, you
take one of these shots. And you can have as much NZT as you want with
no side effects.
BUT the tv series reveales that Morra has worked on a more perminant solution. In 1.12 viewers come to meet Piper Baird, whose someone whom helped create the enzyme that negates NZT's side effects, But Piper believes Morra is trying to keep NZT for himself and so she's trying to kill him for allegedly killing her boyfriend and find a way to replicate the enzyme. So again, we might assume that sometime in between the film and the TV series, Piper had helped Morra get past the booster shot, but it relied on several people & Morra kept the other NZT users, including Piper, from being able to find a better solution (than the immunity shot) for themselves...
1.12 The Assasination of Eddie Morra - Transcript:
Piper: He came to me when I was writing my dissertation. I guess he'd
read some of my work. He told me about NZT, how he was trying to
alleviate the side effects and how, if I could help him do it, the
pill might help my mom.
Finch: You invented the enzyme?
Piper: Well, me and some other people. I don't know who they are.
Morra kept us all separate.
In the season finale, Piper does find a way to replicate the enzyme and makes a formula that gives Brian a perminent solution against NZT-48 Side Effects.
This is also what the Limitless EP Craig Sweeney had to say about these things, in relation to where they would of gone in the second season
Looking to Brian’s newfound permanent immunity, will there be any side
effects? And what can you say about the decision to take that step
now? I think we felt like we had told the story of Brian under the
thumb of Eddie Morra and Sands, and needing to get those clandestine
booster shots. We wanted to move forward from that, basically, and we
felt like the beats would get repetitive if we were telling more
stories where, “Oh, Brian needs to get his booster shot” or “Oh, he
needs to get this file or he won’t get this booster shot.” We did a
lot of things like that, which worked really well.
But we really wanted to have Rebecca and Brian move forward on an honest footing with each other. The need for the immunity shot for
Brian, and the layers of deception that go with it, we cleared the
deck to explore a relationship between Brian and Rebecca in a more
meaningful and honest way.
To get more specific about the way the immunity works, is this a
situation where if someone wanted to replicate it, they could test
Brian and try to duplicate what they find? Or is it in his system in a
way that’s untraceable?
They could certainly try, and it would be interesting. It’s not as if
the FBI knows how to do it yet. They’re definitely going to be
studying him. Piper is not out there, giving it away freely; he is a
kind of Rosetta stone, which makes him a lot of interest to them in
What Brian and Morra’s relationship might be like going forward now
that Brian doesn’t really need him?
A new adversary will emerge in Season 2—who has a history with
Morra—who Morra will take very seriously. Eddie and Brian, instead of
being uneasy adversaries, they’ll be uneasy allies in Season 2.
UDATE: Added Pilot Transcript to better support that Morra was still taking NZT and had some side effects until sometime between the movie and tv series.
Note: A charactacter just saying something is not concrete evidence of truth. However, it does not contradict the film, since we never know for sure, if what Morra tells Van Loon is 100% accurate.