Systemli's Matrix home server instance has a default retention time of 30 days. We allow values from 1-180 days. Sadly, this setting is currently not exposed in Element. If you want to increase/decrease this time, do as follows:

• Find you personal access token in Element by:
  • Click on your username in the upper left corner
  • All settings > Help & About > Advanced
  • Access Token: <click to reveal>
• Find room id in Element by:
  • Click on room info (i) in the upper right corner
  • Room settings > Advanced > Room information
  • Internal room ID: …:systemli.org
• The APi only accept a time in miliseconds, so calulate a new time:
  • 1000*60*60*24*$number_of_days
• Use curl to put another lifetime

curl -X PUT -d '{"max_lifetime": 7}' --header "Authorization: Bearer $your_access_token" 'https://matrix.systemli.org/_matrix/client/r0/rooms/$your_room_id/state/m.room.retention/' 

curl --header "Authorization: Bearer $your_access_token" 'https://matrix.systemli.org/_matrix/client/r0/rooms/$your_room_id/state/m.room.retention'       

If something custom is configured it should return something like

{"max_lifetime":$number_of_miliseconds}

• Matrix Message retention policies
• Matrix Client API documentation