<p>Say I worked with a professor for research for 2 years and then left so I could focus on my major for another academic field. Then, about 1.5 years later I wanted to ask the professor for a letter of recommendation, would I be able to do that after not communicating with the professor since I left? I mean, when application time comes, can I visit the professor and ask for a LOR? (Given that I left on very good terms)</p>
<p>Of course you can. Prof’s are accustomed to be asked LOR from former students and researchers. You might want to give him your CV and some kind of brief write up of the tasks you performed if you think he may appreciate the reminder. You might want to give a heads up now if it is going to be some time before you need the reference.</p>