Is it worth buying the premium?

I’m just asking since I currently don’t have it and I’m wondering if it’s worth paying money for more.

It depends on how much you think you will use the extra things it will grant you. Do you need more universes? Do you want to get more in depth with group dynamics, or do you have made-up races you want to catalog?

You can also think of it more along the lines of, do you want to support the site? Is it giving you a place to store and organize things in a place more convenient than anything else you've found? Then you can view a subscription as tipping the developer.