I think either 1 or these 2 things should be implemented.
1, 1 day every month or 2…a free removal mod day should exist.
2, 1 token to removal all mods given every 1/2 months.
Mods are supposed to be fun, make profit and make your rosters highly customisable.
By limiting the ability to play around and move mods over you are also limiting the fun.
I also think more profit could be made when players realise the mods there missing and encourages them to expand the possibilities.
Atm I think you have turned people away from full utilising them…
From one month to the next a main teaser may be replaced or a function you want a toon to have changes.
You need to give players some space to be creative…and figure out what they want to aim for/buy.
(I realise this isn’t the 1st time this has been suggested. I feel it should get more attention.)