Free antivirus programs use the same deffinition updates as their paid counterparts... the differences from paid to free are insignificant.. things like updating; the paid versions can be programmed to update at the time of day you want, free versions update when you start the computer and again in intervals you can program.... hours, days, etc. Paid versions include a firewall, free versions do not... You have to register free versions once a year, you only have to registre the paid versions when you acquire the license and again when the licensed period ends (if you want to renew the subscription).
Free antivirus never crash for being free, as I said, they use the same update deffinitions as their paid versions. Any antivirus can...