domain name (again!)

while learning the creation of a website, i stubbled on the registration of free domain names, or free for a year.

the question is: are these free or 1-year free registration domain names worth it? do they provide a good service and tools? so close to the purchased domain names. what are their disadvantages?

Note: this is a money website, primary function is affiliating.

Hi, free domain of which extension? doesn't it requires to buy any hosting package or they are just offering it free even if you just take domain only?

Depends on the TLD. Most are not worth it unless you can't spend $1 for .info or $10 for .com.
I found freenom.com few years ago. Free domains (.TK .ML .GA .CF .GQ.) The method i was doing at the time required me to burn through a lot of domains fast. I got tons of domains from them and I made money. Same thing with .xyz domain's a while ago that were being given away like hotcakes for almost nothing.
Then I stopped being a bitch and spent $10 for a .com and my revenue increased 10X with the same traffic/landing page. People trust a .com, not some rinky dink TLD they never heard of.

Better you ask these questions from customer support of the domain selling company.