What is "paid user acquisition"? How would a higher "lifetime value per user" enable you to do it? How is your app monetized to arrive at this LTV? What would it imply for you to have "designed it around monetization from day 1", what would be different? Why can't you change it now?
Paid user acquisition is spending money, usually on ads, to get people to install your app.
The app business is now a ruthless winner-takes-all market and the game is all about spending $3.00 to make $3.05.
When you see pervasive ads for Mobile Strike or Game of War it means that these games are doing a better job of monetization than anyone else so they can buy the users and dominate the top spots in the charts.
Anyway, to advertise for your app, you're competing with every other advertiser out there with products that earn at least a couple dollars per clicking user. If your app only earns $.15 over the lifetime of the person that clicked, you can't afford to take out ads.
As to "Why can't you change it now?" - I haven't figured out a design that would ever allow it to be a high LTV product. So what I do going forward is think very carefully about potential apps through the lens of whether or not they could possibly be high lifetime value. If not, I won't waste my time writing that app.
In closing it is a really really damn hard craft to master, but the multi-dimensional aspect of it keeps it fun.
Lets assume you decide that you want to either make the app profitable or kill it, and the assumption world is simple so there are no other concerns (like eg. you are having fun running a 5 star app): its profit or die.
Given that assumption what would prevent you from changing the app into a subscription based app ("service")? You could notify all your users that from date x/y there will be a monthly fee to use the app. You put it into effect and 99% of your users leave the app. The interesting question left is if remaining useres*monthly fee > monthly cost of app.
Why would that not be an option for you?
NPV calculations, used to determine the value of the entire pipeline, include them.
(Edit: to be clear on definitions, NPV is "Net Present Value")
I have a 5 ⭐️ app, 7 Second Meditation, that has fantastic retention numbers, but I didn't design it around monetization from day 1, so the LTV is too low to do paid user acquisition.
So the app is doomed to putter along on organic installs.
An app must nail both retention and monetization to succeed.
(shameless plug: I did boost the LTV by 45% using https://improve.ai)