What would be the best for creating a new user from another app

[SeaWolf]

What would it take to automatically create a user in the forum when a new user registers on my website and only have access to the forum when their subscription on my website is active?
I know this requires development, but can this be done on one side only (my website)? Or do I need to ask xenforo for development as well?

I hope that's clear, because it's not entirely clear in my mind.

regards
What would be the best for creating a new user from another app

free plugins
minecraft paid for free
mcmarket
mc-market
free minecraft paid plugins
free minecraft plugins
spigotmc
SpigotMC
aac free
ewg free
Minecraft Premium Plugins
ewg free download
litebans free
epicworldgenerator free
free schematics
leaked schematics minecraft
schematics
schematics leaked
schematics free
minecraft schematics free
paid minecraft schematics free
paid minecraft schematics for free
free cracked plugins
free cracked minecraft plugins
plugins
featherboard download
featherboard plugin download
antiaura download
xenforo leaked
xenforo for free
xenforo addons