Yes, you have to create a property for every subdomain since every subdomain has different peculiarities, like the instructions in robots.txt
You may also want to reconsider to put your blog in a subfolder instead a subdomain. This has been the recommedation from Moz for a long time and still is. You can find the explanation here: https://moz.com/blog/subdomains-vs-subfolders-rel-canonical-vs-301-how-to-structure-links-optimally-for-seo-whiteboard-friday