Yes worked before can I buy more RAM somehow? Or is there some workaround its a Lawbook for students, that has become quite big, but I have made the files containing the chapters reasonably small :O)
RStudio Cloud is in beta and as far as I know 1Gb is a hard limit that can't be increased. But in your case I would first try to find out if that's even the case or maybe there is a different problem that you can actually solve (errors in your source code, for example).
Unfortunately, I'm not sure how to check how much memory is currently being used by your R session, but perhaps you can google for it and find something out?