[zer00eyz]

This ask is completely antithetical to how SaaS works.

If your selling them a perpetual license then it is a "shrink wrap" copy of your software, and they get to run it (your not a SaaS any more then)

If they are asking for this, tell them you will sell them a copy of the SaaS for them to run internally - the EULA/contract needs to state that employees and contractors are the only ones allowed to use it, and they can't resell it -

Tell them that you will happily sell it at 5x the 5 year cost and if they need help setting it up/deploy that your hourly rate is $200 an hour, with a 5 hour minimum.