A well kept linocut print has the potential to remain in excellent condition for decades, or even centuries, without yellowing or bleaching.
Yellowing may be caused by high humidity, temperature changes, or use of acidic materials (papers, etc.), whereas sunlight has the tendency to bleach colors. Usually these changes happen slowly, and they may be difficult to spot until it's too late.
Although some prints look great even without a frame, if you wish to make sure that your print stays in the best possible condition, framing is recommended.
Avoid high humidity, and make sure that the print doesn’t come into direct contact with the glass, as this may cause condensation to build up at the point of contact.
In addition to framing, for best results the print should be kept at room temperature, and out of direct sunlight.
To store your print for an extended period of time, for example in a drawer, wrapping the print in acid-free paper will prevent yellowing.