Inventory space is something you always want to increase, and it's no different in My Time At Portia. You begin the game with very limited inventory space, but it's actually very easy to increase it.
You can purchase inventory upgrades from your inventory, so click on your "I" key to open this panel. Now select a locked row and click on "Unlock" to increase your inventory.
This is not free tough, and you need to pay Gol to unlock each row. The first row only costs 300 Gol, but the price gets higher for each new row, so you will gradually be able to increase your inventory as you progress further into the game and has more Gol to spend.
We suggest saving up around 2,000 Gold to purchase the first three rows. This should give you enough inventory space to work with for a while, and then wait to upgrade the rest of the rows until you actually need it.