@Sprucemoose78
All transactions you did add to your account before your subscription switched back into FREE are still in your there, but you cannot add new transactions and you cannot use the other PRO features like add API jobs. And creating a tax report is one of those features as well. A gain calculation with more than 100 trade transactions in total (not per year) is not possible.
You can upgrade your account any time you wish if you need those PRO features. The only thing you need to perform afterwards is described here: https://cointracking.freshdesk.com/a/solutions/articles/29000027952?lang=en