how to handle premium features in a wordpress plugin?

I am developing a plugin in wordpress. I have a question regarding the premium features. How we can manage premium features between free and paid membership?

Are those features already part of plugin but disabled and once payment is made we just enable it? But then what if an average wp plugin developer like me crack those features ?

Is there some kind of encryption used?

I am more interested in saas type of membership. So there has to be a secure key generated to unlock the features. And obviously then features will be disabled again once membership closed or cancelled.

I guess it may be basic question but a big help for me. I would appreciate your support.

Thanks.