Yes you want this - especially since if you are recharging that means you have a leak, the only hope of keeping some of that coolant in there is to help the seals a bit. If you are lucky and it is just the o-rings beign dried up and leaky, your recharge should last a couple of years like my 94 850 has. If your evaporator or condensor is bad then it won't last no matter what.

When your A/C is recharged professionally after repair they also add all those things to the system to lubricate the parts.