Is there a way to protect a folder of photos, in Gallery, from being deleted by the phone?

[AC Question]

When my Moto x, 1st gen, Android 5.1, is becoming too full, it deletes photos, to make up space. Some of these photos are needed to stay on the phone. Is there a way to protect a folder of photos, in Gallery, from being deleted by the phone. I dont want them hidden, just protected from auto delete. I dont mind other photos being cleaned up, since they're all on Photo+, but it's a pain to redownload them when it occurs.