If you would like to buy professional products, here are the guideline for it:
On the main Tanity page, just click on Register (you only have to fill out your e-mail address and your personal password)
After registration simply Log In and go to the Profile menu, where you should fill your billing and shipping details (EU VAT Number if you have). At the end of the form you should find a 'I would like to be a Partner' checkbox, please make shure that it is checked.
Your partner status will be upgraded and you will be able to browse technical and professional products also!