Hello! I'm thinking about purchasing the Destiny base game digitally for PS3, and I'm aware that in doing so I will receive a free digital copy for PS4 on my account in the PS Store. How long will this digital copy stay in my PSN account? Will it ever expire? I plan on getting a PS4, but not in the foreseeable future and I'm worried that I'll have to re-buy it when I own one a while from now. Thank you!