Doubt on clixsense!

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I registered in clix sense and after I logged in,I found that you have to be a premium member to view ads there and it costs $10 to become one.Is it true?I am already at neobux and they don't claim anything like this.Is it worth spending $10 on clixsense and will you earn more in clixsense than in neobux?Please clear my doubts!