In Index Manager, every change is automatically saved in a work file (.idx file). When exporting, the logged information is embedded in the source document. After the export idx must be closed once and opened again to import the document with the now embedded index tags. I personally do this very rarely, perhaps after 800 to 1000 entries. Otherwise the program will be closed during longer breaks.
You can quickly get back to the last place where you left off via the last created index entry.
I usually have the index list sorted by the column No. with the last edited above. Click on the column heading No. and the entries will be displayed in the creation order. With a double click on the uppermost the text jumps to the last entry where you left off.