Based on what law/authority?
Copyright law forbids making copies, derivative works, etc. Not using things. You're allowed to read a book without a license.
Moreover copyright law makes an explicit exception for the copies required to run a computer program on a machine that aren't used in other ways (i.e. copying it to ram/registers): https://www.law.cornell.edu/uscode/text/17/117
The author may say "you can't use this", but it is not clear to me that he has any legal authority to do so.