Unconfirmed txes disappeared in my own bitcoind's mempool
Problem solved. I changed to maxmempool from 300MB to 1GB.

And Murch's comment is what I wanted to know how to transactions leave the memory pool. Thank you!


  Transactions that you're sending yourself should never leave your mempool unless manually evicted or becoming invalid when a doublespend is confirmed. Foreign transactions get evicted after 14 days (previously 3 days), or when mempool is full by lowest fee rate first. You might also be interested in How do transactions leave the memory pool?


Especially, I wanted to know the delete order.


  when mempool is full by lowest fee rate first.