Definitely a fuel stabilizer.
If you're sure you can operate the tractor (long enough to warm it up thoroughly(!!!!) which means running it around for 15-20 minutes) every two or three weeks, I wouldn't do anything else other then keeping the fuel topped off.
However, if that's unlikely, follow the storage methods described in your manual.
If you do not have a manual, or cannot find it; go to the Deere website and look at almost any manual (for a tractor) on that site. Storage is pretty much the same in all the manuals I've looked at (three, so far).
BTW, is this going to be indoor or outdoor storage? In a barn (watch for rodent damage)?
BTW, in the winter, my tractors (had three, so far) have sat for weeks to a month at a time. Other then the fuel treatment and greasing the zerks and loader cylinder rods, I didn't do anything. These machines were kept in a garage in my basement though