The developer of this script does not have an active developer subscription.
Just made a script and uploaded it onto the "gmodstore" and I can't find where to buy a dev subscription. I found that I actually don't have to buy a subscription but it still says "The developer of this script does not have an active developer subscription. You will be unable to purchase the script." Please explain.
It'll be like that until we approve/deny your script.
How long does it usually take to approve/deny a script?
Depends on the circumstance. Usually if you have never submitted a script before -- a little longer because you haven't built a reputation, and the moderators need to ensure that you are a legitimate developer who can create scripts using proper methods and not copy existing work or claiming existing work as your own.
If you've been established here, then sometimes it's a little shorter of a approval time.