Unfortunately, I am not acquainted with Indian Tax law, so I am not able to advice you on this. But, I would presume that if you earn income from affiliate marketing, your profit from the business will be tax under your personal income. That is unless you create a company to run the operation, then it will be subject to corporate tax, and the dividends receive from the company will be subject to your local personal tax.
If you add up all the services you get, the premium membership is a steal. For example, you’ll notice they include unlimited keyword research with a membership. Other paid keyword research tools sell for $49 or more just by themselves. Add in website hosting, and there’s another $10 / mo. Add on the website security package, and there’s another $10 per month (I’ve paid as much as $29 / mo just for website security). Just based on those things alone, Wealthy Affiliate is a great deal with all of the resources and tools you need in one convenient place. Not to mention all of the training, tutorials, and support that is included with the membership.