Do you think you are blameless if you break in and steal the plans?
If the police arrest you for breaking into the office, do you think you'll get off and the client would be charged?
Drop the client, refuse the work, and don't take on any additional work from this client. It's merely a matter of time before they rip you off as well.
If the work requires the use of the software, and you do not already own a license for the software and/or the client is unable/unwilling to provide you with a license, you can't legally use the software - therefore you can't do the work being requested (unless you want to break the law).
In most cases, a freelancer should already own the software necessary to complete their projects. However, on rare occasions work may require specialty software for a single client. It is not unheard of for the client to purchase a license for the software and provide that license to the freelancer. With the understanding that the client owns the software and it is to be used on only their project. In some cases the software is uninstalled or removed from the freelancer's systems once the projects are complete. Any client that "gets around" legally paying for tools they need will "get around" paying your invoices when they are presented. Required tools are a tax deduction and for business there's no viable reason to not pay for them.
This also makes your work in these scenarios a work-for-hire type of agreement since the client is providing tools - you may not want to complete work under a work-for-hire umbrella.
For me personally, if I do not already own software required to complete a project - I examine the costs of the software for my business and the return I would receive on that investment. If possible I look into alternative software to compete the tasks. However, if it is determined that it is not cost effective for my business to purchase a license for a particular software package, then I don't take on work which requires that software.
But there may be ways to keep the project when this problem arises. (but not for clients asking you to steal outright) -- During bidding/quoting and it's determined that specialty software is needed, check the numbers. If profit on a project would make the cost of the software viable - i.e. the project would yield a profit of $5,000 and the software in question is $1,000. So I'd merely cut my profit by purchasing the software. I would seek a (non-refundable) deposit before work began which covered the software cost and initial work to be performed. As stated previously, purchase of software (tools) to complete your work is a tax deduction, so there's no real reason you shouldn't be legal if you are in business.
