Unfortunately, my new job requires windows 7 or 8.1 pro. Huge shame since I actually love 10. Furthermore, windows needs to be fully activated so if I can use bootcamp, I'll need a license. Then, I need to send the laptop to be "configured" which costs 150$ because, of course, they don't use a web-based interface. (financial advisor - sales, client portal and stuff)
The computer is an important tool for the job, I would be using it a lot. My question is, should I buy a win7 license and install it on my 2012 non retina MBP 13 for the single purpose of using the company's advisor interface or purchase an ultrabook?
I won't try to advise you about an ultrabook, but I will second someone else's suggestion: download VirtualBox. You can buy a Windows license from Microsoft and download the ISO. Then, just "boot" the VM from the ISO and go through the setup as usual.
I did so a bit over a year ago for a similar reason: I have financial software that I depend on, and it's only available for Windows. It's the only application I run in the VM. I haven't had a bit of trouble, and I can even snapshot the VM before a major Windows update in case I have problems.
I use it with Windows 8.1. If you want to do this with Windows 10, do a bit of research. The "Windows 10 Advisor" in my Windows 8.1 VM reports that the "VirtualBox Graphics Adaptor for Windows 8" isn't compatible with Windows 10. But, the latest version of VirtualBox (5.0.x) supports Windows 10. You can find several postings with step by step instructions for installing Windows 10 in a VirtualBox VM.
The good news: once you have your Windows VM set up with your employer's software, you can always migrate the VM to another system running VirtualBox if you have to replace your laptop (and avoid another $150 charge). The Windows license manager will complain because the processorID changed, so you can't use it in multiple places at once. I presume that Microsoft would block you from changing it too often.
A potential roadblock: your employer's IT department refuses to install the software on your VM. You may have to gather some information to be sure the DVD drive and USB ports are accessible to the VM. And, you'll have to make sure they know how to start up the VM.