To Check if my software can be cracked and to recommend a solution

I am a freelance programmer, making software packages upon request. Now I have encountered with a company that , requested to check if my software license keys can be cracked or not. I do not have a background about how to check and looking if a freelancer will do it and recommend the best solutions that he knows.

Software can be submitted to the hired freelancer, as it is not critical to share.

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