Are you using the new easy list format perhaps? My daughter has found that it did not auto relist unless she went in & revised the listing to tick the box again after relist from unsold. Even when (3 free) relist is ticked in a new listing it doesn't "stick" & so you only get the 7 or 10 days & no auto relists unless you revise as above.

She has used her 40 free for this month due to this glitch. Whereas I have many listings left. We have similar numbers of listings. I haven't used the new format (& there seems to be no opt out for my daughter!) Though we both list on a desktop computer. not a phone or laptop.

Another annoyance found with that format is only a 3 day postage handling time maximum & no option to extend the timeframe.