How many subdomains

I want to subscribe to the “starter premium“ web hosting. I already have my own domain. I coundn’t find any information about how many subdomains I can have with this plan. (for example: subdomain1 . mydomain . com , subdomain2 . mydomain . com , etc) In iFastNet it states that you get 1 subdomain for the “Starter Premium Hosting” plan. Thanks in advance!