Mipui Business Plan
Mipui is a hobby project ran by one person in his free time. Currently the operating expanses are negligible. Until that changes, no monetization is planned.
If monetization is ever added, though, I'll strive to make it as unobtrusive as possible and without limiting existing features to only paying customers.
For anyone still concerned about Mipui becoming for-pay or blocked or abandoned for some reason, keep in mind Mipui is an open-source project - which means others can bring up independent copies of the app on their own servers.