I installed LR4 on my imac and got the upgrade LR5 on it. I just bought a new macbook pro and i like to install lightroom on my new computer but the problem i only have the LR4 serial number with. How can i proceed please?
Do you mean that you can't find your LR 5 serial number?
You are going to need both serial numbers if you want to install Lightroom 5, because it is an upgrade and bolts serial numbers are required. If you registered Lightroom 5 with Adobe when you first installed it then you can find your serial number on your Adobe account.