Based on different conditions the addon will automatically keep a companion pet summoned for you.
The addon creates a macro labeled EasyPets in the general macro category. Drag it onto your bars. Summon a pet via the Blizzard UI and then Shift+Left Click the macro to set the pet as your current pet. Right click to unsummon the pet. Left click to summon the pet manually. ;)
Notes:
Will not try to summon a pet while you are controlling Razorgore. Will not summon Daisy while she is on your back, nor Cap'n Crackers while he's on your shoulder. If you're having trouble summoning Daisy it's because she is somewhere trying to slowly follow you. Right-click the macro to dismiss her, wherever she is, and left-click again to summon her to where you're at.