Different items have different limits on how many of them you can have in your inventory at once.

Item Max. amount Category
Think Tank 7 Boosts
Loan Shark 9 Boosts
Overclock 9 Boosts
Pistol 10 Gadgets
Time Portal 10 Gadgets
Stolen Time Portal 10 Gadgets
Recruitment Workshop 10 Boosts
Lean Construction 10 Boosts

Recruitment Drive

10 Boosts
Super Charger 12 Gadgets
Super Tool 12 Gadgets
Revival Elixir 25 Boosts
Map 30 Item
Night Vision Binoculars 30 Item
Secure Case 30 Item
Poison Pen 30 Item
Infrared Jammer 30 Item
Anesthetic 49 Item