1.
monthly (rental/contract), by the month
A system of payment or contract calculated on a monthly basis. Most commonly seen on parking lot signs indicating monthly rental spaces.
Usage
Most commonly encountered in the compound 月極駐車場 (monthly parking lot), which is ubiquitous on signs throughout Japan. Also written 月決め. The word can technically apply to any monthly arrangement, but in practice is overwhelmingly associated with parking.
Writing
極 here uses the reading きめ (from 極める, to decide/fix), not the more common on'yomi きょく.