Hello,
it is possible but not as simple as copy and paste.
If on the same server, you may need to change your database's name.
And:
-
in table (ps)_configuration, change PS_SHOP_DOMAIN and PS_SHOP_DOMAIN_SSL into your new subdomain
-
in table (ps)_shop_url, change domain and domain_ssl
(Steps: 1. full backup - 2. on your new subdomain, install the same PS 1.6 - 3. then import files and database - 4. then upgrade to 1.7)
If too scary, you also can do that on a local server on any computer.
Anyway it is a good idea to do a test upgrade before doing it on your true website. Much more safe.