I am currently using the free version of "VMware Workstation Player", but when purchasing the paid version, please tell me whether it is a new version or an upgraded version.
You will be buying a license for the currently available version. If you have this version already installed, you can simply apply the purchased license key to it, i.e. no need to reinstall.
For most VMware products, it is possible to downgrade the purchased key to one for a previous product version, but I'm not sure whether this is possible for "Workstation Player" (simply because I don't own a license for it).