Mamilou

The files can be stored anywhere (eg. Cloud) and loaded later onto your old and or new device. Personally I would download them while they are still available. Some offers are time limited. 

Thank you! Just discovered this area of the forum!

I'm new at using Affinity Photo, but I think that snapshots might help you. For example, start with your original image, do some work in AP using layering as you want, then take a snapshot using the snapshot panel. That should capture all the work you've done and current layers at that point.

Next user Layer->New Layer from Snapshot to create  a new raster layer at the top of the stack from the snapshot you just took. Name this layer, for example, X. That raster layer is, in effect, a flattened version of all the work you've done, but all the original layers are still available below it to modify later if you find something wrong after you run the plugin.
Then apply the plugin to the raster layer X you just created, and continue working from there. Later, if you decided that you needed to redo the plugin work but you had several layers above X, you could delete layer X (leaving the newer layers above it), create a new layer (Y) from the original snapshot, move that layer down the stack to the proper spot, and run the plugin on that layer.
At that point you have the work you did after the plugin still there at the top of the stack to adjust further, then the reworked plugin layer, and below that a set of layers you can effectively ignore unless you need to go back even further to rework things.

NC modules can be used both as standalone applications or a set of plugins. the way you use them depends on your editing goals and workflow.
i seldom use them as standalone applications: actually, only when i need to quickly edit an image whose i don't have the raw original file (i's say, images not taken by me).
in my regular workflow, i always use NC as plugins, as they allow to get results that i cannot reach with AP's native adjustment or live filter layers: i.e. black and white.
as plugins, they are destructive. so, i usually create a copy of the layer i want to apply them to before calling the plugin itself. and, when possible, i try to apply plugins at the very beginning of my editing work or as the very last step.
i hope i didn't misunderstand your question.

To TomWolsky and Alfred
I remember starting on here and finding a James Ritson post that helpfully pointed to an alternative Affinity YouTube page:
https://www.youtube.com/channel/UCQZN-kIrZUQyoTnexM3jJAw/playlists?sort=da&flow=grid&view=1
This has the videos helpfully grouped by theme into playlists that progress you from beginner onwards. In the top right corner, if you click Sort By and choose Date Created (Oldest), you can just work your way down the page as you see fit.
I think this alternative Affinity page deserves to be made the default YouTube portal. It is more useful in getting to grips with the programme.
R

Hi
I know and appreciate both Drippy cat and James Ritson tutorials. I understand mikep and I feel too that I miss longer videos dealing with entire project. A useful bonus would be the initial RAW file, to be able to reproduce the different steps and compare my result to your... 
Perhaps what could be improved is to detail your trials and errors (ie : let us try this tool this this value ... hum ... bad result because this and this, let us try another way, etc.)
 
I don't know if any of you understand french, but I find the following web site to be excellent : http://www.oitregor.com/numeric/affinity_photo/contenu.html 
Many tutorials are missing as today, but this is a structured approach I find perfect for my style of learning. Perhaps having such a roadmap would be a good start.
 
Thanks again for your videos !