My son’s computer seems to have been infected with the absunset trojan although he has the free version of Avast installed on it. My question is, can I buy an Avast license on one computer (my own Mac) and use it on another computer (his Windows)? I don’t really want to enter my credit card info on his computer…
Both Free and paid versions offer the same basic protection. So, not likely a license upgrade will solve the trojan infection on the other computer.
You could upgrade after using a Windows license purchased using the Mac, and paid does offer additional features that will offer protection in areas Free does not for the future, but best to submit logs for the malware expert to clean and diagnose the system infected. Cleaning your system first is priority.