Can I recover the data deleted one year ago or even longer time ago?

Only if the deleted data hasn't been overwritten by the newly-written data on that hard drive, the data can be retrieved with the program.

For example, you have deleted some files on an external hard drive a year ago but if you rarely added new files or edit files on the drive in the past year, the deleted files probably are still on the drive.

Thus, whether the files can be recovered doesn't depend on how long the files have been deleted. You can try to use FonePaw Data Recovery to scan and preview the scanned results to see if the deleted data can be recovered.