How long can home dried herbs be stored?
If properly dried and kept airtight, it will keep safely indefinitely. If it spoils it wasn't dried enough. Active drying should of course be started promptly after picking. But safety of dried herbs is rarely the issue. Loss of flavour is more likely to be the limiting factor. 

Many herbs lose flavour just from the drying process, others stay tasty for a long time, and some are in between - they can handle drying but not for long. I've seen attempts to categorise herbs to predict how well they'll taste good after drying, but haven't found them convincing. Mint and some related species keep fairly well, but basil (for example) isn't really worth drying.