You will need two subscriptions.
You can share the project file back and forth. Media files are much larger, so they become somewhat problematic. If you both already have the media, that's good.
Couple of caveats. First, only one person can work at a time, and you'll have to be in constant communication about who is working and who isn't. Whoever isn't can't touch the project until it's released from whoever is, otherwise you'll just overwrite each other's changes.
Second, unless your hard drive setup is identical on both systems, you'll have to contend with relinking every time you get the project back from the other editor.