Every time a user requests the IP of a smart subdomain, credits are subtracted from your account. Just to make this more clear, by smart subdomains we don't mean normal subdomains, those are free; we mean subdomains linked to scripts. The number of subtracted credits depends on the resources used by your script:

• Basic cost of one smart subdomain request ⇒ 1 credit
• If you activate network name detection (aka Autonomous System Number / AS/ ASN) ⇒ +3 credits
• If you activate city detection (country, city, latitude, longitude…) ⇒ +2 credits
• If you activate country detection ⇒ +1 credit
• If you activate extra info sharing ⇒ +0 credits (free)
• If you activate uptime info sharing ⇒ +0 credits (free)

So each time the IP of a smart subdomain is requested, 1 to 7 credits are subtracted from your account.