Those kind of licenses typically last for years and can be renewed for a new period.
First indication of an expired license is usually when DVD's go OOS/OOP, some retailers even list those.
Then a US citizen could check the license/copyright info on FUNimations web page to see whether an anime is still listed there, or if streams are still available.
Only after that one might consider uploading said anime here, but it remains tricky whether or not a license is truly expired...