[AstralStorm]

This does not work at least for software licensing based on precedents for shrink-wrap contracts, so again would not work for licensing use of data.

A paper served you by the valet is not an immediate contract as you can deny agreeing to it and service does not happen.

You cannot do that with a publicly visible website, unless you show ToS and require agreement before first use. If you allow a non-transferable license then said data cannot be used by a search engine. If it's transferable you just pushed the problem towards scraping a different bot. (Well, you could have a direct agreement with a few major search engines.)

Caveat emptor: not a lawyer.