Memorising Songs

Hello.

Here’s my ‘problem’. I feel like I have the memory of a goldfish. I’m taking lessons, and every time, I’m given a sonf to practise. It all goes well; I can play them properly, but only with the sheet music. Unfortunately, if you take it away, I’m lost.

And worse still, two weeks later, I won’t be able to play that song anymore.

Do you have a method for getting to grips with sheet music better? Without having to have it right in front of me.

And how can I memorise songs properly?