What Is Membership?

It depends what you are talking about.

If you talk about joining a website they can have things that say only for members and stuff so the people that can get it either earned it or paid for it.

Membership is basically being part of a special kind of VIP club because of payment or earning it it is basically being a part of something with advantages that some people probably don't have.

On some things there are levels of membership like bronze silver or gold bronze could mean you are a member for a short period of time or have few advantages silver could be being a member for a little bit longer and having better advantages and gold would be having membership for a long time or just having all advantages

Membership is something that you pay to get one but in different things such as online games or other stuff.