Referencing Management Software - do you pay for subscriptions/storage?

I'm a first year PhD student, and am using Zotero to manage my references for my literature review, however I have already reached my storage capacity. I'm hesitant to pay for additional storage but I really will be needing it.

How do you manage your storage? Other software? Or do you just keep the files on your PC?

I'm UKRI funded, but this doesn't seem like an expense they would cover based on what I've read in the guidelines for my studentship expenses.

I'm also using Litmaps which is a helpful visual tool, but once again the pro version needs to be paid for.

Just looking for any advice or alternatives, thank you!