Premium can be automatically granted to you when you receive a certain number of downloads via CurseForge, and you'll keep the entitlement as long as you continue to receive the required number of downloads. Please note though that the Curse Premium program will be changing in future so I can't guarantee this benefit will remain available long term.
I logged in into Minecraft Forums today and found out I have Curse Premium, yet I didn't make a purchases at all. How did I receive it?
"The perfect way to live is not living in a perfect way." - PixelGX
I thought the same thing. I have it, yet I have made no purchases, only uploaded some maps/resourcepacks, and now I'm apparently a premium.
Premium can be automatically granted to you when you receive a certain number of downloads via CurseForge, and you'll keep the entitlement as long as you continue to receive the required number of downloads. Please note though that the Curse Premium program will be changing in future so I can't guarantee this benefit will remain available long term.
What's the required amount?
I'm not sure, you'd need to reach out to CurseForge support for any specifics on their program. Sorry I can't help further!