Hi!
We have 2 gateways "main" and "edge". Main has Remote Tag Provider configured, so we can see and modify tags in remote edge server. This edge has tag history configured and it has Tag Historian module running. Main one does not have this module. When I try run system.tag.queryTagHistory function on main, it does not return anything. If I activate trial on main it starts to work. Do I need Tag Historian in both servers for this to work or should I change configurations a bit or something?
Yes.
yes!
tag historian is a two part functionality: storage and retrieval. you need tag historian where you have storage (at the edge) and where you consume (main). This has changed in 8.1, see 8.0 to 8.1 Upgrade Guide | Ignition User Manual