Affiliate Marketing

Assalam o Alaikum. I wanted to ask whether setting up an affiliate marketing business is halal or not. I especially wanted to know with respect to promoting online programs. There’s a particular website (Builderall.com) that has an affiliate program where you can promote its programs (which in this case are various types of paid memberships). Now, for every person who gets a membership through your link, you get a 30% commission of the price of that membership. If that user remains an active user and keeps using the program, you’ll keep getting the commission amount in the form of a monthly income, Now, this particular website has a two-tier affiliate program, This means that you keep getting 30% monthly commission from the people who signed up for this program under your affiliate link, and if those people sell that same program to other people below, you also get 30% commission from them (in the second tier). This whole system is not a pyramid or an MLM. Its only a 2 layer system and you can’t earn money beyond the second layer.
However, i still wanted to know whether this hierarchical system of commissions is halal or not,
especially with regards to the 2nd layer where I’m receiving commissions from someone else’s successful sale only because that person had joined the program through my link.

JazakAllah

PS:- here’s the link to the website that offers this affiliate program
https://affiliates.builderall.com/