price change but without affecting the former students

How to change the price of a membership without affecting the ones I already have inside.

For example: let’s imagine that I have students at € 1 and I want them to always pay € 1 a month …. but starting tomorrow all new entrants will be € 2 …
that is, those who entered when they charged € 1 to maintain the price and the new ones have the new price.

it’s possible? how would you do

Thank you