Be aware, theres a bug that doesnt let you build tech for which youve got the blueprints.

currently it seems theres no real cause-effect relationship, although i was under the impression i lost a few because i didnt press the key to show me the inventory after i got the blueprints... whatever it is, just be aware of that bug/glitch.
took me quite a while to find out after i wondered why i couldnt build the tech.

if someone else could test the theory that you always need to press the button to get to the inventory when receiving blueprints to actually get them it would be appreciated.

some other sources:
http://www.gamefaqs.com/boards/739857-no-mans-sky/74142401
http://www.gamefaqs.com/boards/739857-no-mans-sky/74136927
https://www.reddit.com/r/NoMansSkyTheGame/comments/4xhhrx/missing_blueprints/