[GuitarGeni]

There are some good suggestions here but I don’t think it’s realistic to expect to learn songs and not have to refresh them periodically. Our memories, even the muscle kind, simply aren’t that good. I’ve heard many interviews with professionals where they indicate that even though they may have played a song thousands of times, they too forget over time. I’m not sure what your motivation is in the first place. If you’re not planning to play for anyone, what’s the point? If you are, then simply review them ahead of time. If it’s just for bragging rights and saying “I know X number of songs by heart”, that’s just ego not musicianship.