Maybe Stablehost get a deal with .FUN, .ONLINE, .SITE, .STORE, .TECH domain name provider so StableHost can give all customers who are using the domain here for FREE.
In particular, you will be registered each type 1 domain name for free, a total of 5 domains.
When paying only using the FREEDOMAIN coupon the price will be $0.
Visit StableHost and sign up right here.
I have tested the renewal price but do not see the information on the StableHost homepage, but certainly the cost will not be cheap. So consider carefully before deciding.