You can take the batteries out for as long as you like without losing the programming (macros, keymoves, learned signals, VPT, etc.)

BUT, when the manufacturer loads an "upgrade", that process probably does lose all your programming.

If you get a JP1 cable, you can install a better upgrade yourself, and you can start by reading your previous programming from the remote to the PC, so you have it backed up in case of error and so you can merge the upgrade into the previous programming.