* Charge whole numbers, not 4.95. No need for the confusion. Makes the service look cheap.
* Double or triple the price (to $10-15/month). $5 vs $10 is nothing to the average dev, but it halves the number of people you need to get to ramen profitable.
* Have an expensive pro plan ($99 - $299/month). With email support, etc. If nothing else, it makes the less expensive plans more attractive.
* Don't "delete" the free scripts. "Archive" them after 7 days [it's a 7-day free trial] and you can get them all back when you upgrade to pro. If someone wants to "abuse" the system by recreating their scripts every 7 days, fine.
99% of devs will be more familiar with javascript than Lua, so I'd greatly encourage supporting that.