Check out their TOS: https://www.fastly.com/acceptable-use

II. ACCEPTABLE USE Policy

Fastly’s services shall not be used by any person or entity:

in any way that violates any applicable federal, state, local, or international law or regulation; for fraudulent purposes; for the purpose of exploiting, harming, or attempting to exploit or harm minors in any way, including by exposing them to inappropriate content or asking for personally identifiable information; to store, publish, display, or transmit obscene, defamatory, infringing, libelous, harassing, abusive, threatening or otherwise unlawful or tortious material; to store or transmit material in violation of third-party privacy rights; to send unsolicited messages or postings, including bulk commercial advertising or informational announcements and "spam"; to compromise or attempt to compromise the security of any Fastly or third party network, system, server, or account; to impersonate or attempt to impersonate Fastly, Fastly personnel, another subscriber or user, or any other person or entity; or in any way that restricts or inhibits anyone's use or enjoyment of Fastly’s services or which, as determined by Fastly, may harm Fastly or users of Fastly’s services or expose them to liability.