Add function to Verifying license activation

Can be found at https://docs.cryptlex.com/node-locked-licenses/using-lexactivator/using-lexactivator-with-python

The issue only points to the LexActivator Python documentation; start by reading the linked verification section and then locate the package's existing activation API. Clarify the function's inputs, return and error behavior, and expected test location before implementation; done means those requirements are covered and verified against the documented flow.

索引モデルが issue の本文から書いたものです。