CEC does not impact the outcome of the remote needing to be paired daily. Power saver does not impact the outcome of having to pair daily. No, using my phone is not an acceptable solution to this. All the "answers" in this forum do not work to stop this remote behavior from occurring. The fact this is recurring behavior says, to me, this is a Roku software problem. I try your answers and the remote just needs to be paired again the next day. Boo these people. This is poor product design.
Well, hopefully you realize that's not typical. I mean, I don't even pair remotes annually - I pair them when I take a new one out of the box. So something weird is going on. I'm leaning towards some bad bits in a memory chip. But since this is your first and only post, I don't have much to base my guess on. If this has started during your store's return period, I would immediately swap it for another one.
Sorry, none of my 8 remotes paired with 4 different Roku models exhibit this problem, so I don't think this is an overall design issue.
Perhaps if you give us more details about your particular installation (Roku model and model number, powered through TV USB port or house power, type of remote, details of network), someone may have some suggestions for you.