With today's release, the individual file size limit has been raised to 75 MB for Plus accounts and 500 MB for Pro accounts. It has been lowered to 15 MB for new Basic accounts, but preexisting Basic accounts will still use the previous 50 MB limit. The overall storage limits have also been raised accordingly, to 15 GB for Plus accounts and 50 GB for Pro accounts.
This should be enough to accommodate compressed recordings (MP3, M4A) for Basic accounts, uncompressed recordings (AIF, WAV) for Plus accounts and unusually long recordings or high-quality videos for Pro accounts.