|The PAID for version needs to be paid for to activate.|
The only difference between the paid version and the free version is automatic updates and right click scanning for files and I believe online support. The free version is just as effective as the paid version.
Malwarebytes is an antimalware application not an antivirus program.
If you are after an entirely free antivirus program there are plenty on offer.
My preference is Avast, but you can look at others such as AVG and Antivir.
I take it Malware bytes fixed the initial problem?