Thanks Brendan. WYWH isn’t my favourite but I might make a list of riffs to practice once a week that I can put things like that on it. Maybe have a weekly and a monthly list. When I have it right through on the weekly, it moves to the monthly. Some pieces like WYWH I don’t want to learn as songs but wouldn’t mind retaining the riffs to rip off every now and then.
Thanks for your reply!
Thanks everyone for your responses. They’ve been very helpful. What a great forum this is. I can see me visiting here more often.
Have you had a look at Justin’s website lessons? They are free and used in conjunction with the app, should cover everything you need to know. Eventually you’ll have to ditch the ap and strike out on your own. 
Aren’t the lessons in the app the same as those online?
Yes, but the website version has a learn more tab with useful written material complimenting the lesson video etc. You will also find with some lessons Guitar Pro files and backing track files. The last time I checked the app expected you to do improvisation using the C Major Scale and Am pentatonic scale to the sound of silence.
I agree with a lot of the advice given here. I reckon I can keep in memory a maximum of about 10 reasonable length songs. Every song I learn though, I write down the guitar part in a tab book. I can then blow the dust off an old song way quicker than it took to learn it in the first place.
An alternative (or ideally an addition) to writing tab is to record a video of yourself with a closeup on the guitar. I’ve started doing this recently quite a bit.
Within the App, the easiest thing to do is to “favourite” the songs you have learned or are working on - just tap the heart icon for that song, and it will be added to the Favourites list.
Going forward, I’m now getting a lot of benefit from downloading lead sheets and copying them into a word processor. I correct errors (most of them have a few, and some are very inaccurate), format them so my old eyes can read them from a music stand, add playing notes, etc.
This really helps with memorization, and forces you to dig into some of the nuances that you might miss just by playing along with a recording.