That is/was a lifetime ago
A: I was thinking, a year ago, the only thing I ever had to worry about on a weekday was whether or not I`d get to Panny`s soccer practice on time.

B: That is a lifetime ago.

Can I say "That WAS a lifetime ago."?

Thank you.

Question

That is/was a lifetime ago
A: I was thinking, a year ago, the only thing I ever had to worry about on a weekday was whether or not I`d get to Panny`s soccer practice on time.

B: That is a lifetime ago.

Can I say "That WAS a lifetime ago."?

Thank you.

Answer

When you are using the present tense, it means that it is still a valid fact.  When you use past time, you are indicating the event had happened long ago.

Answer

Yes "that was a lifetime ago" is better to say because the word "ago" refers to something that has already happened in the past. 
I hope this helps :D

Answer

That was a lifetime (one word) ago.