Buy this:
https://www.ebay.com/itm/Homelink-Un...JZpJAI&vxp=mtr
Recess it somewhere in your visor/headliner/overhead console/dash.
It needs to be powered when it is on to use it obviously, it DOES ABSOLUTELY YES maintain it's memory/rolling codes when off. Just tap a hot wire, either hot on ignition or always hot... something for example like onstar power or similar.
You can also add a 12v battery if you really want.