Time to pay the piper, every year.
I don't know how many are aware of this, so I'm posting some important information.
Starting January 1st next year (2018) PTC will make it's products available by subscription only.
https://www.ptc.com/en/news/2017/ptc-accelerates-subscription-business-model
Basically, legal ransomware. If you don't keep paying them, you will be denied access to your own IP.
My understanding is that this new scheme will apply to all PTC products, other than one obscure product, so that includes Mathcad. I believe that existing perpetual licenses will continue to be perpetual (hard to see how it could be anything else, since that's how they were sold), but going foward you will either have to pay every year, or lose access to your own work.

