Atif,
It should work from a technical standpoint, but it is definitely skirting the EULA. To protect yourself, I would recommend sending them an e-mail recommending they purchase the license required to scan all of their IPs. We used to have similar issues with Bindview licensing where we could get around license limitations by scoping just under the license count and I always advised against it. In the end, no company wants the stigma of violating license terms.
Chris Tyrrell
Compliance Practice Lead
Conventus Corp.
ctyrrell@conventus-sei.com