Assuming you want to update from version 5.x to 5.y, there are basically two scenarios:
1) Installing the newer version directly
over your existing install folder will keep all settings, etc. (so usually no extra steps necessary here).
2) If you're doing, for instance, a
portable Reaper
install to a different location, you'll need to import the
reaper-license.rk file for this install again. Either via the menu or by copying the license file into the Reaper resource folder (
Options > Show REAPER resource path in explorer/finder).
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As a side note: it's a good strategy in general to make regular backups (and before updating to a newer version) of your configurations, just in case
https://www.youtube.com/watch?v=HB4C3njFxRg
So if you haven't already, this might be a good time to do this, as well