"LastFM" -> "Last.fm" anywhere that it says LastFM now. Reason: brand identity rules
Change "Pause" to "Enable Scrobbling" (and have it checked by default). This matches what the older desktop scrobbling apps do. Also Pause sounds like it's to do with pausing the song
Popups: change "…just started playing" to "…is now playing"
Popups: remove "Accepted: " or "Rejected: " from the UI. (These could still appear in the logs…)