Most users coming to the page have the Free Basic plan, and will trend toward having less technical knowledge.
Being primarily price-driven, users will be most inclined to choose between the Starter and Pro plan and will need to know they key differences between the two from a benefit standpoint, which should be clear and prominent.
I determined the primary benefit or key differentiating factor between the two is the “Set it and forget it” type of protection Pro offers, moreso than the frequency of malware removal operations.
A potential strategy would be doing a user story for each plan selection, wherein choosing Starter would require the hassle of first getting the malware (which may go undetected for an indeterminate amount of time), then performing a manual scan, engaging in email/chat support, possible loss of data or reputation due to malware, and cost in terms of time and effort.
Avoidance of pain as well as peace of mind can be major motivations in choosing the plan with a slightly higher price.