Hi,
thanks for your response,
I have a one-year ArcGIS for Desktop Student Trial licence, which I got from one of the Coursera lessons. It will be expiring in a few weeks.
I think I actually managed to save my work though, despite Esri Support telling me that all my content will be deleted and that my only option is to purchase an "ArcGIS for Personal Use license" at $100/year...
Nobody ever mentioned to me this possibility and I never realised it, but I can actually create an ArcGIS Public Account!
"An ArcGIS public account is a free account designed for personal, non-commercial use.
With a public account you can:
Create, store, and manage maps, scenes, layers, apps, and other geospatial content.
Share content with others.
Access content shared by Esri and GIS users around the world."
So, one can actually do a lot of stuff with this free account! This is perfect for me, I just need this type of account to store my content, that's it.