you are missing the point completely, if your plugin is a trial offer state it upfront like all other trial software does then the user can make a decision immediately. trial buried 6 feet under … 1591 words down is the first mention of trial. this is the very reason why many will not purchase your product. be upfront, back your product, if you need penetration, ask … the wordpress community would warm up to that idea more than being tricked into downloading a trial plugin.
btw, could premium also not be free? and vaultpress clearly states
“VaultPress is a subscription service offering realtime backup, automated security scanning, and support from WordPress experts.”
thanks for the lesson. please take this away from this comment, be transparent and state TRIAL upfront.