At now most of popular messages (Telegram, Facebook, Viber, WhatsApp, ICQ, etc) have ability to store chat logs on server and retrieve history from server, sync history between devices. Opensource XMPP IM servers Ejabberd and Prosody already have build-in support for XEP-0313 Message Archive Management, so this is easy to enable now on any XMPP server. Please add ability to retrieve and sync chat log message from archive on server in next versions of Kopete, this is very useful feature. Some other Jabber clients already impement this feature, for example Gajim, Converse.js (full list is here https://www.zash.se/mam.html) - maybe we can re-use code from this project?
It is already listed as idea for GSoC: https://community.kde.org/GSoC/2017/Ideas#Kopete For XEP-0136: Message Archiving there are also initial patches: https://git.reviewboard.kde.org/r/111361/
Dear user, unfortunately Kopete is no longer maintained. Please migrate to another solution, e.g. for Jabber a possibility is Kaidan, for Matrix a candidate is NeoChat.