Before spending your money on anything, of course you want to be fully aware of what you are actually buying into. You need to know if you can afford it, and if it meets your requirements. You need to be sure that you will be able to use it effectively (does the program include training, instruction and support). You need to know how it works and what is included (the basics as well as any resources available to members). Very importantly for any affiliate program, you need to be aware of any special circumstances that may be part of the compensation plan.
There is usually a lot more to it than that you pay so much for the membership and you receive a percentage of the cost in commissions when you make a sale. The special circumstances could mean that you are ‘passing up’ a commission to your sponsor or giving them a percentage of each