Assalaamu alaykum wa rahmatullaah wa barakaatuhu. There are sites that offer email marketing advertising and earnings. They are free to use and advertise and earn a commission. They also have memberships that are designed to give advertisers better advertising results, but they also give higher commission on sales (buyers that we bring to the site) than on free memberships. People buy it for many reasons, some because of advertising benefits only, and some because of a higher commission. My question is: is it haram or halal to buy this membership? May Allaah reward you.

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

It is not permissible to buy a membership for the benefits of advertising or for high commissions and so on because this is a form of forbidden gambling as the person who buys the membership pays money hoping to gain profits; he may get the profits, and he may not gain anything and lose money, and Allaah says (what means): {O you who have believed, indeed, intoxicants, gambling, [sacrificing on] stone altars [to other than Allaah], and divining arrows are but defilement from the work of Satan, so avoid it that you may be successful.} [Quran 5:90]

Allaah knows best.