Can masturbation cause erectile disfunction in later years?

No: There is no link between masturbation & erectile dysfunction. However, excessive masturbation may make it difficult to achieve orgasm via sex w/partner if you're "used to" specific action/friction/means of achieving orgasm. But do understand that what's excessive to one person might be nothing to someone else. With that said, if you only engage in masturbation, you're at very low risk for an std.