No, the service is free for everyone who has their own user account on Tietokettu. You can activate the affiliate program only from the customer area!
Yes, if you are a business customer. As a private customer, you also get credits, but you can't just transfer them to your account. In both options, you can also freely use credits to order Tietokettu.net services / pay your bills.
You can see your credits by first logging into the customer area and then clicking on the clock at the top.
You need to have a commission of 25€ in order to redeem credits for yourself from products.