Yes, you can’t copy and paste the license key or write an “@” sign because Reaper is programmed in a way that DAW shortcuts overwrite actions that are taken in the plugin. That’s an issue many plugin manufacturers have with Reaper, and it’s specifically with German keyboard formats (since the “@” is “Alt/Option+L”, which is a Reaper shortcut). The only way to work around this is by temporarily changing your keyboard format to US. Then you can hit “Shift+2” in order to get the “@” symbol. Unfortunately, the license key still needs to be typed in manually. We hope Reaper will fix this issue soon.