Gali būti naudojamas prieš, or perhaps naudojamas prieš, but I did not take it from the bottom of a product. I have only Lithuanian honey at home and it says: best before. You should wait for someone who has contemporary Lithuanian products at home. but my options should be OK. You need the diacritics, and I don't have them on this computer, but you can easily Google the phrase and see the necessary diacritical marks.
Hello. Where did you get the terms from? The first one does not look right. Reikia žiūrėti ant dugno. You have to look at the bottom. Your phrase is in the infinitive: to look at the bottom.
Geriausoia iki -- best till. There are also different genders and numbers of the nouns in Lithuanian so the form will depend if you are talking about apples or sugar. These could be used like that in a generic sense. It would be best to see what companies in Lithuania use. I will try to do some research.
Hello, Adiigiampaolo, again. I am convinced that these phrases are conventionally used: Galioja iki 01.12.15
Galiojimo data: 01.12.15
These are usually used in reference to cosmetics and medicine, other chemicals, possibly food as well, certain types.
There is: suvartoti iki - use until, or to be used until 01/12/15
Geriasias iki - best before, but you could use it even a few days after the date, because it is not the final expiration date. These are mostly used for food, such as meat, cans, other things as well.
I think you could use your infinitives like you wanted -- look at the bottom, or on the package. It should be fine.