Every researcher will need to think about how to acquire the full text articles identified through literature searches. You can often get copies of the articles you need for free through one of the options below.
If you are affiliated with a university, the library is the best place to start looking for full text. The library will have subscription access to many articles. It will probably be able to get you copies of others through inter-library loan. If you are searching a database like FSTA, each record will link straight to the library's copy of the full text article (if they have one).
Check with your library if you need help getting the full text of a published article.
Anyone, affiliated with a university or not, can get the full text of open access articles. Using a browser extension like Unpaywall can help you source free legal open access copies of articles.
Databases and libraries also often link directly to open access articles.
Google Scholar will sometimes link you to legal versions of an article or conference proceeding. Search the full title of the item, inside quotation marks, to check if this option works or not. It may lead you to a researcher platform. Find more information about those on the next tab.
On ResearchGate and Academia.edu an author might make a copy available to download, or let you request a copy.
To use either platform, you need to register for a free account.
Be aware: the articles supplied through these sites are sometimes manuscript drafts or pre-prints, which should only be used with caution, rather than the peer-reviewed version of record. You might decide one is useful enough to invest in the journal-published version for your research.
If you cannot get an article through your library by locating an open access copy, you can write to the corresponding author to ask them to send you a copy of their article. The information to reach them is part of the article record. It can look like this:
Or it might look like this:
When you know a patent's title or publication number (which you will find in a database that includes patents, like FSTA) the free patent sites Espacenet or Google Patents will usually lead you to the full text document.
Get full text with Espacenet
Espacenet often leads to full original downloadable patent documents, and also collates patent families, linking together patent applications for the same content filed with patent offices around the world. To find a patent: 
Get full text with Google Patents
Sometimes Google Patents results will include a downloadable PDF version of a patent and sometimes only an HTML version.
Go directly to a country’s patent office search
In the rare cases that Espacenet or Google Patents fail to retrieve a patent’s text, try googling the issuing patent office. Translate the page, if necessary, to find how to proceed.
Learn more: Finding and Retrieving Food Science and Nutrition Patents (ifis.org)
If you do not have access to library collections, you might need a budget for acquiring papers. Remember that you will not need to get the full text of every article you find with your searches. The information available in the abstracting and indexing record is often enough to determine if an article is relevant enough to your research question to need to read the full text.
If you will need to purchase some articles, be sure to establish your budget before you begin. Wait to make your purchasing decisions until you have run your searches and gone through your initial screening process.
There are various forms of intellectual property (IP) rights which protect assets such as discoveries, inventions, and literary and artistic works, including research. In many cases, IP rights begin automatically when the work is created. The owner of these rights may sell them or issue licences to allow others to make use of an asset. If copyright is infringed, the owner can seek damages or an injunction to prevent further infringements.
It is important to comply with the law in acquiring and using research articles and other material. Copyright laws around the world tend to grant exceptions (sometimes called Fair Use or Fair Dealing) to allow people to use materials for research done for non-commercial purposes. Even in these circumstances restrictions apply on what you can do you with the research—for instance, you can only download a certain proportion of the articles in a single issue of a journal, you cannot share the full text of an article you have not written unless the article has been published as open access, and you must always properly cite any work you use. Your librarian will be able to advise you further on intellectual property (IP) and copyright protection of any materials you wish to use in research. If you are conducting research for commercial purposes, you will need to familiarise yourself and comply with the law.
BEST PRACTICE RECOMMENDATION: if you are affiliated with a university, be sure to learn how to take full advantage of their subscriptions and inter-library loan services to get the full text articles you need. Don't overlook what is available to you for free because you haven't learned to use your library!