Question: is it illegal to not pay for a service

Answer: Yes, Theft of services is the legal term for a crime which is committed when a person obtains valuable services -- as opposed to goods -- by deception, force, threat or other unlawful means, i.e., without lawfully compensating the provider for these services. It may also overlap with some types of fraud in which payment is made on credit, but under an assumed identity, and ultimately disavowed (``identity theft'').