The Item Of The Month (IOTM) was implemented into the game on 2nd of March 2017.
Every month, a limited item is made available in the Growtopia Store, where it can be bought for a certain amount of Gems. The Item Of The Month of March, April, May, and June of 2017 all cost 100,000 Gems. Since July 2017, the price for the IOTM rose to 200,000 Gems to increase their value. During January 2021, the price for IOTM rose to 350,000 Gems to keep the item's value when then they are no longer in the store.
The item is only available in the store for one month, and once it is taken out of the store, it can never be obtained again.
This was later changed upon the release of the Grow Pass update on October 5, 2021 where the term was changed to Item Of The Season featuring two variants of the item, the normal and royal variant. The normal variant of the Item Of The Season can be obtained by Royal Grow Pass users while accumulating 150 Grow Pass Points by completing quests and tasks or by accumulating 2,100 Grow Pass Points which will be available in the Growtopia Store for Gems once the season ends. The royal variant of the Item Of The Season can exclusively be obtained by Royal Grow Pass users while accumulating 2,100 Grow Pass Points.
The IOTMs can be seen on the Growtopia Forums.