When Google deprecated goo.gl, every link ever created through it eventually stopped working — years of embedded links in documents, printed materials, and old posts broke at once. That's the real risk of depending on any shortener: you're trusting someone else's infrastructure to keep resolving your link indefinitely.
Linqeezy's answer is a real policy, not just a promise: there is no code anywhere in this product that deletes a link for being old or unused. A link made today works the same way in five years. The only things that can take a link down are a Terms-of-Service violation (see Terms) or Linqeezy itself shutting down entirely — the same caveat any service has to be honest about.