Why is this setup as a subscription model?

This app is based on financial parameters that change constantly and need annual and monthly updates to stay current and provide the most accurate estimate possible. In addition to these updates, there are new features to be added quarterly based on customer feedback. Here are some of the key parameters that need updating across the 23 supported countries:
1. Federal and state tax brackets
2. Retirement account tax rules by country (i.e. what age you can use funds without penalty and the penalty amount).
4. Inflation rates
5. College costs
6. Social security benefits
7. YTD Asset class performance for current year
8. Household budget averages by country
9. Cost of living index by country