Serial no. issues- is my version of photoshop too old?

I have a version 7.0 of Photoshop elements on my computer which was installed in 2009.

I  now have a laptop and would like to transfer a copy of the programme

onto my laptop to use. I have accessed the serial no. from my adobe account

but after downloading the programme on my laptop,when prompted to

enter the serial no. it is rejected. How can I rectify this and get the

programme on my laptop?

any help would be much appreciated thank you!