when i download UE4 i can only open and use 4.2.1 but i cant use 4.5 ? how come? do i need to re-subscribe, cant i just use it to ONLY test my work. (which is in 4.5)
You will need an active subscription to download the latest versions of the editor, whichever version was available when you canceled your subscription will be the newest one available for you to use.
You can re-subscribe for one month and download the latest version as well if you’d like. 
awesome thank you that is what i needed to know. 
cheers mate
Bear in mind if you currently have 4.2.1 and resubscribe and download 4.5 you will have both full versions of the engine installed on your computer, even if you delete the 4.2 from the launcher (which are about 10GB each.) is OK if you have the space. Otherwise, make sure your projects in your Documents folder are backed up and delete an earlier version as shown here:
