Version upgrades usually include two main contents, one is to correct errors（Fix bugs), and the other is to enhance functions or add new functions. 

My suggestion is: Divide version upgrades into two categories by marking and distinguishing version upgrade numbers: 

the first type of upgrade (Error correction) is free; the second type of upgrade (New addition) is charged! 

Please verify this real-life scenario: the reason why the number of users who purchase or use the una application platform is growing slowly?! That is not because there is insufficient investment in marketing, but because there are too many bugs encountered during use or trial!