How long do LORs keep?

I recognize that there are quite a few LOR advice threads floating around, but I'm afraid I still have a question about them: is it acceptable to obtain a letter from a professor if you know you will not be applying for 2+ years? I ask because, like many in the nontrad forum, I did not realize that I wanted to pursue medicine until after I left college. However, as I graduated only this year (and from a very small school), my professors definitely still remember me quite well. Would it be acceptable to ask them for a LOR the next time I'm in town, let them take their time on it, and send it to Interfolio to be stored until the application cycle? It will probably be at least 2 years before I use them, as my lack of focus in UG leaves me in need of a semi-serious GPA repair postbacc and, of course, I have zero EC's outside of research. Additionally, my PI (for whom I wrote a thesis) retired this year and I am not certain how much longer she plans on being affiliated with my school...I would love to get a reference from her, but that may not be possible (not to mention polite) 2 years down the line. :scared: Thoughts?
Source: Student Doctor Network Forums - Category: Universities & Medical Training Authors: Tags: Nontraditional Students Source Type: forums