Great program on Windows 10 PC and other devices albeit it is slow even if you buy upgrades. On Windows 10 PCs, it basically doesn't work although it will work on a PC upgraded to Windows 10. Many complaints and no solution from Sugarsync.
3GB free, 30GB very reasonably priced. I now, very simply, keep 5 computers in sync and backed up.
Terrific service, works very well - I synchronize a "magic folder" across desktop, laptop, home computers.