How many single-use computer programs are used in everyday life? Not files. The whole program. Go through the expense of installing this new software, which in the Traveller Universe, is nearly impossible. (Traveller made data storage unlimited but for some reason copying data almost impossible.) Build one item, and now your expensive Fabricator is now useless again. Can you imagine having to go to the store to buy a new copy of Excel because you want to make one more spreadsheet? Also, after purchase you need to wait for a company authorized technician to install it in your Fabricator, as anyone else installing it is a breach of contract and will void your purchase.
It would make more sense that you can get an unlimited template for everything used by the SPA for a nominal fee. This is how the SPA keeps standardization across the 3I.